Avelino F Arellano

Interests

Research

atmospheric chemistry modeling and data assimilation, satellite remote sensing of atmospheric composition, biomass burning, anthropogenic pollution, urbanization

Teaching

data assimilation, atmospheric composition, air pollution, computational methods, physical meteorology, remote sensing

Courses

Scholarly Contributions

Chapters

• Friedli, H. R., Arellano, A. F., Cinnirella, S., & Pirrone, N. (2009). Mercury emissions from global biomass burning: Spatialand temporal distribution. In Mercury Fate and Transport in the Global Atmosphere. Springer US. doi:10.1007/978-0-387-93958-2_8
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  This chapter represents a new addition to the UNEP global mercury budget: the mercury emissions from biomass burning, here defined as emissions from wildfires and prescribed burns, and excluding contributions from bio-fuel consumption and charcoal production and use. The results cover the 1997-2006 timeframe. The average annual global mercury emission estimate from biomass burning for 1997-2006 is 675 ± 240 Mg yr-1. This accounts for 8% of all current anthropogenic and natural emissions. The largest Hg emissions are from tropical and boreal Asia, followed by Africa and South America. They do not coincide with the largest carbon biomass burning emissions, which originate from Africa. Our methodology for budget estimation is based on a satellite-constrained bottom-up global carbon fire emission database (GFED version 2), which divides the globe into regions with similar ecosystems and burn behaviour. To estimate mercury emissions, the carbon model output is paired with regional emission factors for Hg, EF(Hg). There are large uncertainties in the budget estimation associated with burned area, fuel mass, and combustion completeness. The discrepancy between the model and traditional ground based assessments (e.g. FRA, 2000) is unacceptably large at this time. Of great urgency is the development and validation of a model for mercury cycling in forests, accounting for the biogeochemistry for each region. This would provide an understanding of the source/sink relationship and thus mercury accumulation or loss in ecosystems. Limiting the burning of tropical and boreal forests would have two beneficial effects: reducing the source of mercury releases to the atmosphere from burning, and maintaining a sink for atmospheric mercury. Restricting the global release mercury would reduce the vegetation/soil pools, and the potential Hg release in case of fire. © 2009 Springer-Verlag New York.

Journals/Publications

• Ajayi, T., Mirrezaei, M. A., Arellano, A. F., Robinson, E. S., & Sorooshian, A. (2025).

  A long-term (2001-2022) examination of surface ozone concentrations in Tucson, Arizona

  . Environ. Sci.: Atmos., 5, 1326-1340.
• Ajayi, T., Mirrezaei, M. A., Arellano, A. F., Robinson, E. S., & Sorooshian, A. (2025). A long-term (2001–2022) examination of surface ozone concentrations in Tucson, Arizona. Environmental Science: Atmospheres. doi:10.1039/d5ea00072f
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  Ground-level ozone (O3) pollution in semi-arid regions like Tucson, Arizona, presents unique challenges due to the interplay of anthropogenic emissions, biogenic volatile organic compounds (BVOCs), meteorological conditions, and regional transport. Tucson is the second-largest city in Arizona and has received comparatively less attention than the most populated city of Phoenix despite experiencing elevated O3 levels amid rapid population growth. This study provides a comprehensive 22 year analysis (2001–2022) of O3 trends in Tucson using a combination of ground-based monitoring data, satellite observations, NEI emissions inventories, land cover classification and meteorological datasets. The findings reveal no statistically significant long-term trend in O3 levels at northwest (NW), urban core, and south/southeast (S/SE) monitoring sites despite regulatory actions to reduce precursor levels. However, spatial differences persist with one S/SE site (Saguaro National Park) consistently exhibiting the highest O3 concentrations and an urban core site (Rose Elementary) usually exhibiting the lowest values across all seasons. Satellite and surface-based data reveal a decline in NO2 across the study period, in contrast to HCHO levels that show little long-term change, with a brief increase in 2020 likely linked to regional fire activity and higher temperatures, particularly in June. Consequently, FNR values (formaldehyde-to-NO2 ratio) increased after 2005–2009, indicating a regional shift influenced by reductions in NOx emissions, especially during fall/winter and spring. This shift helps explain the weakening of the weekend effect (i.e., higher weekend levels versus weekdays) over time and the emergence of the weekday effect earlier in the summer (June) in contrast to the late 1990s. Generalized additive model meteorology normalization suggests that 79% of the O3 variability is attributed to interannual weather variability. FNR started to decline post-2020, suggesting changes in O3 responsiveness to further NO2 reductions, particularly in cooler months. These dynamics, along with recent fall/winter O3 increases, highlight the complex, chemical regime-dependent response of O3 to precursor changes. This study recommends improved VOC characterization to inform future air quality strategies in the region.
• Fraser, M., Arellano, A. F., Herckes, P., Robinson, E., & Sorooshian, A. (2025).

  Feeling the Heat: Ground Level Ozone Research (GLOR) Ramps up in Maricopa County

  . EM Magazine, 21-25.
• Furlong, M. A., Paul, K. C., Parra, K. L., Fournier, A. J., Ellsworth, P. C., Cockburn, M. G., Arellano, A. F., Bedrick, E. J., Beamer, P. I., & Ritz, B. (2025). Preconception and first trimester exposure to pesticides and associations with stillbirth. American Journal of Epidemiology, 194(Issue 1). doi:10.1093/aje/kwae198
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  Associations of pesticide exposures during preconception with stillbirth have not been well explored. We linked Arizona pesticide use records with birth certificates from 2006 to 2020 and estimated associations of living within 500 m of any pyrethroid, organophosphate (OP), or carbamate pesticide applications during a 90-day preconception window or the first trimester, with stillbirth. We considered a binary measure of exposure (any exposure), as well as log-pounds and log-acres applied within 500 m, in a negative control exposure framework with log-binomial regression. We included 1 237 750 births, 2290 stillbirths, and 27 pesticides. During preconception, any exposure to pesticides was associated with stillbirth, including cyfluthrin (risk ratio [RR] = 1.97; 95% CI, 1.17-3.32); zeta-cypermethrin (RR = 1.81; 95% CI, 1.20-2.74); OPs as a class (RR = 1.60; 95% CI, 1.16-2.19); malathion (RR = 2.02; 95% CI, 1.26-3.24); carbaryl (RR = 6.39; 95% CI, 2.07-19.74); and propamocarb hydrochloride (RR = 7.72; 95% CI, 1.10-54.20). During the first trimester, fenpropathrin (RR = 4.36; 95% CI, 1.09-17.50); permethrin (RR = 1.57; 95% CI, 1.02-2.42); OPs as a class (RR = 1.50; 95% CI, 1.11-2.01); acephate (RR = 2.31; 95% CI, 1.22-4.40); and formetanate hydrochloride (RR = 7.22; 95% CI, 1.03-50.58) were associated with stillbirth. Interpretations were consistent when using continuous measures of pounds or acres of exposure. Pesticide exposures during preconception and first trimester may be associated with stillbirth.
• Guo, Y., Mirrezaei, M. A., Sorooshian, A., & Arellano, A. F. (2025).

  Source contribution to ozone pollution during June 2021 in Arizona: Insights from WRF-Chem tagged O3 and CO

  . Atmospheric Chemistry and Physics. doi:https://doi.org/10.5194/acp-25-5591-2025
• Guo, Y., Mirrezaei, M. A., Sorooshian, A., & Arellano, A. F. (2025). Source contribution to ozone pollution during June 2021 fire events in Arizona: insights from WRF-Chem-tagged O3 and CO. Atmospheric Chemistry and Physics, 25(Issue 11). doi:10.5194/acp-25-5591-2025
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  This study quantifies wildfire contributions to O3 pollution in Arizona, relative to local and regional emissions. Using WRF-Chem with O3 and CO tags, we analyzed emissions during June 2021, a period of drought, extreme heat, and wildfires. Our results show that background O3 accounted for ∼ 50 % of total O3, while local anthropogenic emissions contributed 24 %–40 %, consistent with recent estimates for Phoenix. During peak smoke conditions, fire-related O3 ranged from 5 to 23 ppb (5 %–21 % of total O3), averaging 15 ppb (15 %). These estimates were compared with model sensitivity tests excluding fire emissions, which confirmed the spatiotemporal pattern of fire-driven O3, though the model underestimated the magnitude by a factor of 1.4. The results further demonstrate that wildfires exacerbate O3 exceedances over urban areas. Our analysis reveals key differences in O3 sources: Phoenix’s O3 was mainly driven by local emissions, while Yuma’s was heavily influenced by transboundary transport from California and Mexico. Wildfires not only boosted O3 formation but also altered winds and atmospheric chemistry in Phoenix and downwind areas. O3 increases along the smoke plume resulted from NOX and volatile organic compound (VOC) interactions, with fire-driven O3 forming in NOX-limited zones near the urban interface. Downwind, O3 chemistry shifted, shaped by higher NOX in central Phoenix and more VOCs in suburban and rural areas. Winds weakened and turned westerly near fire-affected areas. This study highlights the value of high-resolution modeling with tagging to disentangle wildfire and regional O3 sources, particularly in arid regions, where extreme heat intensifies O3 pollution, making accurate source attribution essential.
• Lorenzo, G. R., Ziemba, L. D., Arellano, A. F., Barth, M. C., Crosbie, E. C., DiGangi, J. P., Diskin, G. S., Ferrare, R., Hilario, M. R., Shook, M. A., Tilmes, S., Wang, J., Xiao, Q., Zhang, J., & Sorooshian, A. (2025). Measurement report: Characterization of aerosol hygroscopicity over Southeast Asia during the NASA CAMP2Ex campaign. Atmospheric Chemistry and Physics, 25(Issue 11). doi:10.5194/acp-25-5469-2025
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  This study characterizes the spatial and vertical nature of aerosol hygroscopicity in Southeast Asia and relates it to aerosol composition and sources. Aerosol hygroscopicity via the light scattering hygroscopic growth factor, f(RH), is calculated from the amplification of PM5 (particulate matter with a particle diameter, Dp, < 5 µm) scattering measurements from < 40 % to 82 % relative humidity during the Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex) between August and October 2019 over the northwest tropical Pacific. Median f(RH) is low (1.26 with lower to upper quartiles of 1.05 to 1.43) like polluted environments, due to the dominance of the mixture of organic carbon and elemental carbon. The f(RH) is lowest due to smoke from the Maritime Continent (MC) during its peak biomass burning season, coincident with high carbon monoxide concentrations (> 0.25 ppm) and pronounced levels of accumulation-mode particles and organic mass fractions. The highest f(RH) values are linked to coarser particles from the West Pacific and aged biomass burning particles in the region farthest away from the MC, where f(RH) values are lower than typical polluted marine environments. Convective transport and associated cloud processing in these regions decrease and increase hygroscopicity aloft in cases with transported air masses exhibiting increased organic and sulfate mass fractions, respectively. An evaluation of the Community Atmosphere Model with Chemistry (CAM-chem) for cases of vertical transport showed the underrepresentation of organics, resulting in overestimated modeled aerosol hygroscopicity. These findings on aerosol hygroscopicity can help to improve aerosol representation in models and the understanding of cloud formation.
• Lorenzo, G. R., Ziemba, L. D., Arellano, A. F., Barth, M. C., Crosbie, E. C., DiGangi, J. P., Diskin, G. S., Ferrare, R., Hilario, M., Shook, M. A., Tilmes, S., Wang, J., Xiao, Q., Zhang, J., & Sorooshian, A. (2025).

  Measurement report: Characterization of aerosol hygroscopicity over Southeast Asia during the NASA CAMP²Ex campaign

  . Atmospheric Chemistry and Physics, 25(11), 5469--5495.
• Mirrezaei, M. A., Gaubert, B., Arellano Jr., ,., Fernandez, R. P., Ortega, I., Emmons, L. K., Kinnison, D., Roozitalab, B., McKain, K., Bruhwiler, L., Oh, Y., Saiz-Lopez, A., Cuevas, C. A., Feng, C., Xu, Y., & Brasseur, G. P. (2026).

  Toward Realistic Prognostic Modeling of the Methane Chemical Loss

  . Journal of Geophysical Research: Atmospheres, 131(1), e2025JD045079.
• Pan, K., Tangborn, A., Anderson, J. L., Santanello, J. A., Carroll, B. J., Demoz, B., & Arellano, A. F. (2025).

  Assimilation of Doppler Lidar-Derived Planetary Boundary Layer Height Measurements Using an Ensemble Kalman Filter: Case Studies during the PECAN Field Campaign

  . Journal of Applied Meteorology and Climatology, 64(10), 1467 - 1487.
• Parakkat, L., Hilario, M., Mirrezaei, M. A., Robinson, E. S., Arellano, A., & Sorooshian, A. (2025). Ozone concentrations and influential variables during heat waves over two desert cities in the Southwest U.S.. Environmental Research Communications, 7(12), 125008.
• Roychoudhury, C., He, C., Kumar, R., & Arellano Jr., ,. A. (2025). Diagnosing aerosol--meteorological interactions on snow within Earth system models: a proof-of-concept study over High Mountain Asia. Earth System Dynamics, 16(4), 1237--1266.
• Roychoudhury, C., Kumar, R., He, C., Cheng, W., Ram, K., Mizukami, N., & Arellano, A. F. (2025). MATCHA, a novel regional hydroclimate-chemical reanalysis: System description and evaluation. Earth System Science Data Discussions, 2025, 1--73.
• Shohan, S., Koch, S. E., Castro, C. L., Arellano, A. F., Kay, J., Risanto, C. B., Weckwerth, T. M., Pinto, J. O., & Adams, D. K. (2025). Impact of Assimilating GPS Precipitable Water Vapor on Simulations of Two North American Monsoon Convective Events Using Observing System Simulation Experiments. Journal of Geophysical Research: Atmospheres, 130(16), e2025JD044491.
• Shohan, S., Koch, S. E., Castro, C. L., Arellano, A. F., Kay, J., Risanto, C. B., Weckwerth, T. M., Pinto, J. O., & Adams, D. K. (2025). Impact of Assimilating GPS Precipitable Water Vapor on Simulations of Two North American Monsoon Convective Events Using Observing System Simulation Experiments. Journal of Geophysical Research: Atmospheres, 130(Issue 16). doi:10.1029/2025jd044491
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  This study evaluates the impact of assimilating precipitable water vapor (PWV) within an observing system simulation experiment (OSSE) framework to improve forecasts of monsoonal mesoscale convective systems (MCSs) in Arizona. Two contrasting case studies differing in convective forcing, longevity, intensity, and coverage are analyzed using a 40-member ensemble of 1.8-km resolution Weather Research and Forecasting (WRF) convective-permitting model (CPM) simulations including the Data Assimilation Research Testbed (DART) system. Synthetic PWV data are derived from a nature run (NR) and bias corrected using real GPS-derived PWV observations from a campaign during the North American monsoon (NAM) season 2021. These synthetic PWV are assimilated in an inferior model simulation called the control run (CR) to avoid the identical twin problem. Horizontal GPS station spacing experiments (e.g., superobbed, 50 km, 100 km, and 200 km) are conducted to identify configurations that maximize forecast skills. Assimilating the synthetic PWV reduces mean errors (∼2 mm) and dry bias during the first 4–6 hr of the predictions using analyses improved with PWV data assimilation. The 100-km GPS network optimally captures convective precipitation patterns, outperforming coarser (200-km) and finer (50-km) grids due to an improved representation of moisture and winds afforded by PWV data assimilation at the appropriate scales. Topography strongly influences moisture distribution, with elevation-dependent biases, overestimation in low elevations (0–500 m), underestimation in midelevations (500–2,000 m), and systematic high-elevation (>2,000 m) biases due to vertically integrated PWV constraints. This study provides actionable insights for optimizing GPS network design and improving convective-scale modeling in arid/semiarid regions.
• Betito, G., Arellano, A., & Sorooshian, A. (2024). Influence of Transboundary Pollution on the Variability of Surface Ozone Concentrations in the Desert Southwest of the US: Case Study for Arizona. Atmosphere, 15(4), 401.
• Furlong, M. A., Paul, K. C., Parra, K. L., Fournier, A. J., Ellsworth, P. C., Cockburn, M. G., Arellano, A. F., Bedrick, E. J., Beamer, P. I., & Ritz, B. (2024). Preconception and first trimester exposure to pesticides and associations with stillbirth. American Journal of Epidemiology, 194(1), 44-55.
• Gaubert, B., Anderson, J. L., Trudeau, M., Smith, N., McKain, K., P??tron, G., Raeder, K., Arellano Jr, ,., Granier, C., Emmons, L. K., Ortega, I., Hannigan, J. W., Tang, W., Worden, H. M., Ziskin, D., & Edwards, D. P. (2024). Nonlinear and Non-Gaussian Ensemble Assimilation of MOPITT CO. Journal of Geophysical Research: Atmospheres, 129(12), e2023JD040647.
• Gaubert, B., Anderson, J. L., Trudeau, M., Smith, N., McKain, K., Pétron, G., Raeder, K., Arellano, A. F., Granier, C., Emmons, L. K., Ortega, I., Hannigan, J. W., Tang, W., Worden, H. M., Ziskin, D., & Edwards, D. P. (2024). Nonlinear and Non-Gaussian Ensemble Assimilation of MOPITT CO. Journal of Geophysical Research: Atmospheres, 129(Issue 12). doi:10.1029/2023jd040647
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  Satellite retrievals of carbon monoxide (CO) are routinely assimilated in atmospheric chemistry models to improve air quality forecasts, produce reanalyzes and to estimate emissions. This study applies the quantile-conserving ensemble filter framework, a novel assimilation algorithm that can deal with non-Gaussian and modestly nonlinear distributions. Instead of assuming normal distributions like the Ensemble Adjustments Kalman Filter (EAKF), we now apply a bounded normal rank histogram (BNRH) distribution for the prior. The goal is to efficiently estimate bounded quantities such as CO atmospheric mixing ratios and emission fluxes while maintaining the good performance achieved by the EAKF. We contrast assimilating meteorological and MOPITT (Measurement of Pollution in the Troposphere) observations for May 2018. We evaluate the results with the fourth deployment of the NASA Atmospheric Tomography Mission (ATom-4) airborne field campaign. We also compare simulations with CO tropospheric columns from the network for the detection of atmospheric composition change and surface in-situ observations from NOAA carbon cycle greenhouse gases. While the differences remain small, the BNRH approach clearly works better than the EAKF in comparison to all observation data sets.
• Greenslade, M., Guo, Y., Betito, G., Mirrezaei, M. A., Roychoudhury, C., Arellano, A. F., & Sorooshian, A. (2024). On ozone's weekly cycle for different seasons in Arizona. Atmospheric Environment, 334(Issue). doi:10.1016/j.atmosenv.2024.120703
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  This study advances insights on ozone (O3) concentration temporal cycles in Arizona, exploring differences between weekdays and weekends to understand the impact of anthropogenic activities on O3 fluctuations. By examining data from six areas across Arizona and with a more detailed look across the Phoenix metropolitan area, this study compares O3 and NO2 levels based on day of the week and time of day as well as during five distinct seasons between January 2015 and December 2021: fall (Sep–Nov), winter (Dec–Feb), spring (Mar–May), dry summer (June), and monsoon summer (Jul–Aug). Results highlight associations between O3 levels and O3 precursor levels, particularly for nitrogen oxides (NOx) and volatile organic compounds (VOCs). Results show that O3 levels are contingent on diurnal, day-of-week, and seasonally-dependent factors. This dependence influences the phenomena called the “weekend effect”, which is most clearly observed at urban sites across Arizona in fall and winter seasons, wherein O3 concentrations exhibit higher levels during weekends compared to weekdays. This study reveals opposing features during Arizona's warmer months and especially the monsoon summer period in which O3 regimes reverse from VOC-sensitive (in fall and winter) to transition and NOx-sensitive regimes. A specific case study for Phoenix during the first COVID-19 lockdown (spring 2020) accounting for planetary boundary layer height normalization of gas concentrations shows that although NO2 was reduced in March–April compared to other years, O3 was also reduced due to a regional O3 response as most areas surrounding western U.S. were typically either transitioning to, or already under, a NOx-limited regime. These findings provide insights into understanding the intricate relationship among anthropogenic emissions, seasonal fluctuations, and pollutant emissions and transport that influence O3 levels across Arizona, potentially providing guidance for future study designs focused on effective control strategies for the sensitive months with most exceedances (∼June–August).
• Greenslade, M., Guo, Y., Betito, G., Mirrezaei, M. A., Roychoudhury, C., Arellano, A. F., & Sorooshian, A. (2024). On ozone's weekly cycle for different seasons in Arizona. Atmospheric Environment, 334, 120703.
• Guo, Y., Roychoudhury, C., Mirrezaei, M. A., Kumar, R., Sorooshian, A., & Arellano, A. F. (2024). Investigating Ground-Level Ozone Pollution in Semi-Arid and Arid Regions of Arizona Using WRF-Chem v4.4 Modeling. Geoscientific Model Development. doi:https://doi.org/10.5194/gmd-17-4331-2024
• Guo, Y., Roychoudhury, C., Mirrezaei, M. A., Kumar, R., Sorooshian, A., & Arellano, A. F. (2024). Investigating ground-level ozone pollution in semi-Arid and arid regions of Arizona using WRF-Chem v4.4 modeling. Geoscientific Model Development, 17(Issue 10). doi:10.5194/gmd-17-4331-2024
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  Ground-level ozone (O3) pollution is a persistent environmental concern, even in regions that have made efforts to reduce emissions. This study focuses on the state of Arizona, which has experienced elevated O3 concentrations over past decades and contains two non-Attainment areas as designated by the U.S. Environmental Protection Agency. Using the Weather Research and Forecasting with Chemistry (WRF-Chem) model, we examine O3 levels in the semi-Arid and arid regions of Arizona. Our analysis focuses on the month of June between 2017 and 2021, a period characterized by high O3 levels before the onset of the North American Monsoon (NAM). Our evaluation of the WRF-Chem model against surface Air Quality System (AQS) observations reveals that the model adeptly captures the diurnal variation of hourly O3 levels and the episodes of O3 exceedance through the maximum daily 8g2h average (MDA8) O3 concentrations. However, the model tends to overestimate surface NO2 concentrations, particularly during nighttime hours. Among the three cities studied, Phoenix (PHX) and Tucson (TUS) exhibit a negative bias in both hourly and MDA8 O3 levels, while Yuma demonstrates a relatively large positive bias. The simulated mean hourly and MDA8 O3 concentrations in Phoenix are 44.6 and 64.7 parts per billion (ppb), respectively, compared to observed values of 47.5 and 65.7g2ppb, resulting in mean negative biases of 2-2.9 and 2-1.0g2ppb, respectively. Furthermore, the analysis of the simulated ratio of formaldehyde (HCHO) to NO2 (2HCHO/NO2; FNR), reveals interesting insights of the sensitivity of O3 to its precursors. In Phoenix, the FNR varies from a VOC (volatile organic compound)-limited regime in the most populated areas to a transition between VOC-limited and NO2x-limited regimes throughout the metro area, with an average FNR of 1.15. In conclusion, this study sheds light on the persistent challenge of ground-level O3 pollution in semi-Arid and arid regions, using the state of Arizona as a case study.
• Hilario, M. R., Arellano, A. F., Behrangi, A., Crosbie, E. C., Digangi, J. P., Diskin, G. S., Shook, M. A., Ziemba, L. D., & Sorooshian, A. (2024). Assessing potential indicators of aerosol wet scavenging during long-range transport. Atmospheric Measurement Techniques, 17(Issue 1). doi:10.5194/amt-17-37-2024
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  As one of the dominant sinks of aerosol particles, wet scavenging greatly influences aerosol lifetime and interactions with clouds, precipitation, and radiation. However, wet scavenging remains highly uncertain in models, hindering accurate predictions of aerosol spatiotemporal distributions and downstream interactions. In this study, we present a flexible, computationally inexpensive method to identify meteorological variables relevant for estimating wet scavenging using a combination of aircraft, satellite, and reanalysis data augmented by trajectory modeling to account for air mass history. We assess the capabilities of an array of meteorological variables to predict the transport efficiency of black carbon (TEBC) using a combination of nonlinear regression, curve fitting, and k-fold cross-validation. We find that accumulated precipitation along trajectories (APT) - treated as a wet scavenging indicator across multiple studies - does poorly when predicting TEBC. Among different precipitation characteristics (amount, frequency, intensity), precipitation intensity was the most effective at estimating TEBC but required longer trajectories (>48h) and including only intensely precipitating grid cells. This points to the contribution of intense precipitation to aerosol scavenging and the importance of accounting for air mass history. Predictors that were most able to predict TEBC were related to the distribution of relative humidity (RH) or the frequency of humid conditions along trajectories, suggesting that RH is a more robust way to estimate TEBC than APT. We recommend the following alternatives to APT when estimating aerosol scavenging: (1) the 90th percentile of RH along trajectories, (2) the fraction of hours along trajectories with either water vapor mixing ratios>15gkg-1 or RH>95%, and (3) precipitation intensity along trajectories at least 48h along and filtered for grid cells with precipitation>0.2mmh-1. Future scavenging parameterizations should consider these meteorological variables along air mass histories. This method can be repeated for different regions to identify region-specific factors influencing wet scavenging.
• Miech, J. A., Herckes, P., Fraser, M. P., Arellano, A. F., Mirrezaei, M. A., & Guo, Y. (2024). Evaluating Phoenix Metropolitan Area Ozone Behavior Using Ground-Based Sampling, Modeling, and Satellite Retrievals. Atmosphere, 15(5), 555.
• Miech, J. A., Herckes, P., Fraser, M. P., Arellano, A. F., Mirrezaei, M. A., & Guo, Y. (2024). Evaluating Phoenix Metropolitan Area Ozone Behavior Using Ground-Based Sampling, Modeling, and Satellite Retrievals. Atmosphere, 15(Issue 5). doi:10.3390/atmos15050555
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  An oxidizing and harmful pollutant gas, tropospheric ozone is a product of a complex set of photochemical reactions that can make it difficult to enact effective control measures. A better understanding of its precursors including volatile organic compounds (VOCs) and nitrogen oxides (NOx) and their spatial distribution can enable policymakers to focus their control efforts. In this study we used low-cost sensors (LCSs) to increase the spatial resolution of an existing NO2 monitoring network in addition to VOC sampling to better understand summer ozone formation in Maricopa County, Arizona, and observed that afternoon O3 values at the downwind sites were significantly correlated, ~0.27, to the morning NO2 × rate values at the urban sites. Additionally, we looked at the impact of wildfire smoke on ozone exceedances and compared non-smoke days to smoke days. The average O3 on smoke days was approximately 20% higher than on non-smoke days, however, the average NO2 concentration multiplied by estimated photolysis rate (NO2 × rate) values were only 2% higher on smoke days. Finally, we evaluated the ozone sensitivity of the region by calculating HCHO/NO2 ratios using three different datasets: ground, satellite, and model. Although the satellite dataset produced higher HCHO/NO2 ratios than the other datasets, when the proper regime thresholds are applied the three datasets consistently show transition and VOC-limited O3 production regimes over the Phoenix metro area. This suggests a need to implement more VOC emission controls in order to reach O3 attainment in the county.
• Mirrezaei, M. A., Arellano, A., Guo, Y., Roychoudhury, C., & Sorooshian, A. (2024). Ozone production over arid regions: insights into meteorological and chemical drivers. Environmental Research Communications, 6(5), 051009.
• Mirrezaei, M. A., Arellano, A., Guo, Y., Roychoudhury, C., & Sorooshian, A. (2024). Ozone production over arid regions: insights into meteorological and chemical drivers. Environmental Research Communications, 6(Issue 5). doi:10.1088/2515-7620/ad484c
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  Arid urban areas are pivotal in the global landscape, and their air quality issues are highlighted by the complexities of tropospheric ozone production. Here, we use recent satellite observations from TROPOMI and a longer record of data from OMI to investigate the levels of ozone precursors (NO2 and CH2O) in 12 major cities in arid regions. Using a space-based CH2O/NO2 indicator, we identified the dominant chemical regime influencing ozone formation, revealing a clear temporal trend that aligns with previously reported economic trajectories as well as variation in emission control strategies implemented in these cities. Our results show that, NO2 concentrations decreased in cities with proactive regulatory policies, such as Madrid and Los Angeles in semi-arid and arid regions. A contrasting increase was observed in rapidly developing cities within arid and hyper-arid regions, such as Tehran and Cairo, where emission controls are less strict. An increase in CH2O levels was also apparent, requiring more attention to VOCs control. Furthermore, our analysis clearly shows that the interactions between ozone production and climatic factors such as temperature exhibit a nonlinear relationship, especially in arid climates. These findings highlight the importance of emission reduction strategies that consider the meteorological and chemical drivers of dry regions, particularly in light of the rising global aridity.
• Mottungan, K., Roychoudhury, C., Brocchi, V., Gaubert, B., Tang, W., Mirrezaei, M. A., McKinnon, J., Guo, Y., Griffith, D. W., Feist, D. G., Morino, I., Sha, M. K., Dubey, M. K., De Mazière, M., Deutscher, N. M., Wennberg, P. O., Sussmann, R., Kivi, R., Goo, T. Y., , Velazco, V. A., et al. (2024). Local and regional enhancements of CH4, CO, and CO2 inferred from TCCON column measurements. Atmospheric Measurement Techniques, 17(Issue 19). doi:10.5194/amt-17-5861-2024
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  In this study, we demonstrate the utility of available correlative measurements of carbon species to identify regional and local air mass characteristics as well as their associated source types. In particular, we combine different regression techniques and enhancement ratio algorithms with carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) total column abundance from 11 sites of the Total Carbon Column Observing Network (TCCON) to infer relative contributions of regional and local sources to each of these sites. The enhancement ratios provide a viable alternative to univariate measures of relationships between the trace gases that are insufficient in capturing source-type and transport signatures. Regional enhancements are estimated from the difference between bivariate regressions across a specific time window of observed total abundance of these species (BERr for bulk enhancement regression ratio) and inferred anomalies (AERr for anomaly enhancement regression ratio) associated with a site-specific background. Since BERr and AERr represent the bulk and local species enhancement ratio, respectively, its difference simply represents the site-specific regional component of these ratios. We can then compare these enhancements for CO2 and CH4 with CO to differentiate between combustion and non-combustion air masses. Our results show that while the regional and local influences in enhancements vary across sites, dominant characteristics are found to be consistent with previous studies over these sites and with bottom-up anthropogenic and fire emission inventories. The site in Pasadena shows a dominant local influence (> 60 %) across all species enhancement ratios, which appear to come from a mixture of biospheric and combustion activities. In contrast, Anmyeondo shows more regionally influenced (> 60 %) air masses associated with high-temperature and/or biofuel combustion activities. Ascension Island appears to only show a large regional influence (> 80 %) on CO / CO2 and CO / CH4, which is indicative of transported and combustion-related CO from the nearby African region, consistent with a sharp rise in column CO (3.51 ± 0.43 % ppb yr-1) at this site. These methods have important applications to source analysis using spaceborne column retrievals of these species.
• Mottungan, K., Roychoudhury, C., Brocchi, V., Gaubert, B., Tang, W., Mirrezaei, M. A., McKinnon, J., Guo, Y., Griffith, D., Feist, D. G., Morino, I., Sha, M. K., Dubey, M. K., De, M. M., Deutscher, N. M., Wennberg, P. O., Sussmann, R., Kivi, R., Goo, T., , Velazco, V. A., et al. (2024). Local and regional enhancements of CH$_4$, CO, and CO$_2$ inferred from TCCON column measurements. Atmospheric Measurement Techniques, 17(19), 5861--5885.
• Pan, K., Arellano, A. F., Guo, Y., & Demoz, B. (2024). Investigating the Impact of Multiphysics on Modeled Planetary Boundary Layer Height Estimates during the PECAN Field Campaign. Journal of Applied Meteorology and Climatology, 63(11), 1385 - 1407.
• Sorooshian, A., Arellano, A. F., Fraser, M. P., Herckes, P., Betito, G., Betterton, E. A., Braun, R. A., Guo, Y., Mirrezaei, M. A., & Roychoudhury, C. (2024). Ozone in the Desert Southwest of the United States: A Synthesis of Past Work and Steps Ahead. ACS ES&T Air. doi:https://doi.org/10.1021/acsestair.3c00033
• Sorooshian, A., Arellano, A. F., Fraser, M. P., Herckes, P., Betito, G., Betterton, E. A., Braun, R. A., Guo, Y., Mirrezaei, M. A., & Roychoudhury, C. (2024). Ozone in the Desert Southwest of the United States: A Synthesis of Past Work and Steps Ahead. ACS ES\&T Air, 1(2), 62-79.
• Tang, W., Gaubert, B., Emmons, L., Ziskin, D., Mao, D., Edwards, D., Arellano, A., Raeder, K., Anderson, J., & Worden, H. (2024). Advantages of assimilating multi-spectral satellite retrievals of atmospheric composition: A demonstration using MOPITT CO products. Atmospheric Measurement Techniques, 1--30. doi:https://doi.org/10.5194/amt-17-1941-2024
• Tang, W., Gaubert, B., Emmons, L., Ziskin, D., Mao, D., Edwards, D., Arellano, A., Raeder, K., Anderson, J., & Worden, H. (2024). Advantages of assimilating multispectral satellite retrievals of atmospheric composition: a demonstration using MOPITT carbon monoxide products. Atmospheric Measurement Techniques, 17(Issue 7). doi:10.5194/amt-17-1941-2024
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  The Measurements Of Pollution In The Troposphere (MOPITT) is an ideal instrument to understand the impact of (1) assimilating multispectral and joint retrievals versus single spectral products, (2) assimilating satellite profile products versus column products, and (3) assimilating multispectral and joint retrievals versus assimilating individual products separately. We use the Community Atmosphere Model with chemistry with the Data Assimilation Research Testbed (CAM-chem+DART) to assimilate different MOPITT carbon monoxide (CO) products to address these three questions. Both anthropogenic and fire CO emissions are optimized in the data assimilation experiments. The results are compared with independent CO observations from TROPOspheric Monitoring Instrument (TROPOMI), the Total Carbon Column Observing Network (TCCON), NOAA Carbon Cycle Greenhouse Gases (CCGG) sites, In-service Aircraft for a Global Observing System (IAGOS), and Western wildfire Experiment for Cloud chemistry, Aerosol absorption and Nitrogen (WE-CAN). We find that (1) assimilating the MOPITT joint (multispectral; near-IR and thermal IR) column product leads to better model-observation agreement at and near the surface than assimilating the MOPITT thermal-IR-only column retrieval. (2) Assimilating column products has a larger impact and improvement for background and large-scale CO compared to assimilating profile products due to vertical localization in profile assimilation. However, profile assimilation can outperform column assimilations in fire-impacted regions and near the surface. (3) Assimilating multispectral and joint products results in similar or slightly better agreement with observations compared to assimilating the single spectral products separately.
• Yuan, S., Arellano, A. F., Knickrehm, L., Chang, H. I., Castro, C. L., & Furlong, M. (2024). Towards quantifying atmospheric dispersion of pesticide spray drift in Yuma County Arizona. Atmospheric Environment, 319(Issue). doi:10.1016/j.atmosenv.2023.120262
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  While pesticide vapor and particles from agricultural spray drift have been reported to pose a risk to public health, limited baseline ambient measurements exist to warrant an accurate assessment of their impacts at community-to-county-wide scale. Here, we present an initial modeling investigation of the transport and deposition of applied pesticides in an agricultural county in Arizona (Yuma County), to provide initial estimates on the corresponding enhancements in ambient levels of these spray drifts downwind of application sites. With a 50 × 50 km domain, we use the dispersion model CALPUFF with meteorology from the Weather Research and Forecasting (WRF) to investigate the spatiotemporal distribution of pesticide abundance due to spray drift from a representative sample of nine application sites. Data records for nine application days in September and October 2011, which are the peak months of pesticide application, were retroactively simulated for 48-h for all nine application sites using an active ingredient lambda-cyhalothrin, which is a commonly-used pesticide in the county. Twenty-one WRF/CALPUFF simulations were conducted with varying emissions, chemical lifetime, deposition rate, application height, and meteorology inputs, allowing for an ensemble-based analysis on the possible ranges in modeled abundance. Our results show that dispersion of vapors released at time of application heavily depends on prevailing meteorology, particularly wind speed and direction. Dispersion is limited to thin plumes that are easily transported out of the domain. The ensemble-mean vapor concentrations of the 48-h average (> 90 percentile domain-wide) range from 0.2 nanograms(ng)/m3 to 200 ng/m3, and the peak can be as high as 1000 ng/m3 near the application sites. Pesticide particles are mainly deposited within 1–2 km from the application sites at an average rate of 106ng/km2/h but vary with particle mean diameter and standard deviation. While these findings are generally consistent with reported ambient levels in the literature, the associated ensemble-spread on these estimates are in the same order of magnitude as their ensemble-mean. At the two nearby communities downwind of these sites, we find that peak vapor concentrations are less than 50 ng/m3 with exposure times of less than an hour, as approximately 99.4% of the vapors are advected out and 99.5% of the particles deposit within the domain. Results of this study indicate pesticide spray drift from a sample of application sites and representative days in Fall may have a limited impact on neighboring communities. However, we strongly suggest that field measurements should be collected for model validation and more rigorous investigation of the actual scale of these impacts when the bulk of pesticide applications across the county, variation in active pesticide ingredients, and potential resuspension of deposited particles are considered.
• Yuan, S., Arellano, A. F., Knickrehm, L., Chang, H., Castro, C. L., & Furlong, M. (2024). Towards quantifying atmospheric dispersion of pesticide spray drift in Yuma County Arizona. Atmospheric Environment, 319, 120262.
• Gaubert, B., Edwards, D. P., Anderson, J. L., Arellano, A. F., Barr'e, J., Buchholz, R. R., Darras, S., Emmons, L. K., Fillmore, D., Granier, C., & others, . (2023). Global Scale Inversions from MOPITT CO and MODIS AOD. Remote Sensing, 15(19), 4813.
• Hilario, M., Arellano, A. F., Behrangi, A., Crosbie, E. C., DiGangi, J. P., Diskin, G. S., Shook, M. A., Ziemba, L. D., & Sorooshian, A. (2024). Assessing potential indicators of aerosol wet scavenging during long-range transport. Atmospheric Measurement Techniques, 17(1), 37--55. doi:https://doi.org/10.5194/amt-17-37-2024
• Lorenzo, G. R., Arellano, A. F., Cambaliza, M. O., Castro, C., Cruz, M. T., Di Girolamo, L., Gacal, G. F., Hilario, M. R., Lagrosas, N., Ong, H. J., Simpas, J. B., Uy, S. N., & Sorooshian, A. (2023). An emerging aerosol climatology via remote sensing over Metro Manila, the Philippines. Atmospheric Chemistry and Physics, 23(Issue 18). doi:10.5194/acp-23-10579-2023
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  Aerosol particles in Southeast Asia are challenging to characterize due to their complex life cycle within the diverse topography and weather of the region. An emerging aerosol climatology was established based on AErosol RObotic NETwork (AERONET) data (December 2009 to October 2018) for clear-sky days in Metro Manila, the Philippines. Aerosol optical depth (AOD) values were highest from August to October, partly from fine urban aerosol particles, including soot, coinciding with the burning season in insular Southeast Asia when smoke is often transported to Metro Manila during the southwest monsoon. Clustering of AERONET volume size distributions (VSDs) resulted in five aerosol particle sources based on the position and magnitude of their peaks in the VSD and the contributions of specific particle species to AOD per cluster based on MERRA-2. The clustering showed that the majority of aerosol particles above Metro Manila were from a clean marine source (58%), which could be related to AOD values there being relatively low compared to other cities in the region. The following are the other particle sources over Metro Manila: fine polluted sources (20%), mixed-dust sources (12%), urban and industrial sources (5%), and cloud processing sources (5%). Furthermore, MERRA-2 AOD data over Southeast Asia were analyzed using empirical orthogonal functions. Along with AOD fractional compositional contributions and wind regimes, four dominant aerosol particle air masses emerged: two sulfate air masses from East Asia, an organic carbon source from Indonesia, and a sulfate source from the Philippines. Knowing the local and regional aerosol particle air masses that impact Metro Manila is useful in identifying the sources while gaining insight into how aerosol particles are affected by long-range transport and their impact on regional weather.
• Lorenzo, G. R., Arellano, A. F., Cambaliza, M. O., Castro, C., Cruz, M. T., Di Girolamo, L., Gacal, G. F., Hilario, M., Lagrosas, N., Ong, H. J., Simpas, J. B., Uy, S. N., & Sorooshian, A. (2023). An emerging aerosol climatology via remote sensing over Metro Manila, the Philippines. Atmospheric Chemistry and Physics, 23(18), 10579--10608.
• Risanto, C. B., Moker, J. M., Arellano, A. F., Castro, C. L., Serra, Y. L., Luong, T. M., & Adams, D. K. (2023). On the Collective Importance of Model Physics and Data Assimilation on Mesoscale Convective System and Precipitation Forecasts over Complex Terrain. Monthly Weather Review, 151(8), 1993 - 2008.
• Roychoudhury, C., He, C., Kumar, R., McKinnon, J. M., & Arellano Jr., ,. (2022). On the Relevance of Aerosols to Snow Cover Variability Over High Mountain Asia. Geophysical Research Letters, 49(18), e2022GL099317.
• Liang, J., Chen, Y., Arellano, A. F., & Mamun, A. A. (2021). Model Sensitivity Study of the Direct Radiative Impact of Saharan Dust on the Early Stage of Hurricane Earl. Atmosphere, 12(9).
• Liang, J., Chen, Y., Arellano, A. F., & Mamun, A. A. (2021). Model sensitivity study of the direct radiative impact of saharan dust on the early stage of hurricane earl. Atmosphere, 12(Issue 9). doi:10.3390/atmos12091181
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  Current studies report inconsistent results about the impacts of Saharan dust on the development of African Easterly Waves (AEWs), the African Easterly Jet (AEJ), and tropical cyclones (TCs). We present a modeling case study to further elucidate the direct radiative impacts of dust on the early development stage of a TC. We conducted experiments using the Weather Research and Forecasting model coupled with chemistry (WRF‐Chem‐V3.9.1) to simulate Hurricane Earl (2010) which was influenced by the dusty Saharan Air Layer (SAL). We used the aerosol product from ECMWF MACC‐II as the initial and boundary conditions to represent aerosol distribution, along with typical model treatment of its radiative and microphysical effects in WRF. Our simulations at 36‐km resolution show that, within the first 36 h, the presence of dust weakens the low‐pressure system over North Africa by less than 1 hPa and reduces its mean temperature by 0.03 K. Dust weakens and intensifies the AEJ at its core and periphery, respectively, with magnitudes less than 0.2 m/s. Dust slightly shifts the position of 600 hPa AEW to the south and reduces its intensity prior to impacting the TC. Finally, TC with dust remains weaker.
• Lorenzo, G. R., Ba\~naga, P. A., Cambaliza, M. O., Cruz, M. T., AzadiAghdam, M., Arellano, A., Betito, G., Braun, R., Corral, A. F., Dadashazar, H., Edwards, E., Eloranta, E., Holz, R., Leung, G., Ma, L., MacDonald, A. B., Reid, J. S., Simpas, J. B., Stahl, C., , Visaga, S. M., et al. (2021). Measurement report: Firework impacts on air quality in Metro Manila, Philippines, during the 2019 New Year revelry. Atmospheric Chemistry and Physics, 21(8), 6155--6173.
• RISANTO, C. B., CASTRO, C. L., ARELLANO, A. F., MOKER, J. M., & ADAMS, D. K. (2021). The impact of assimilating gps precipitable water vapor in convective-permitting wrf-arw on north american monsoon precipitation forecasts over northwest mexico. Monthly Weather Review, 149(Issue 9). doi:10.1175/mwr-d-20-0394.1
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  We assess the impact of GPS precipitable water vapor (GPS-PWV) data assimilation (DA) on short-range North American monsoon (NAM) precipitation forecasts, across 38 days with weak synoptic forcing, during theNAMGPS Hydrometeorological Network field campaign in 2017 over northwest Mexico. Utilizing an ensemble-based data assimilation technique, the GPS-PWV data retrieved from 18 observation sites are assimilated every hour for 12 h into a 30-member ensemble convective-permitting (2.5 km) Advanced Research version of the Weather Research and Forecasting (WRF-ARW) Model. As the assimilation of the GPS-PWV improves the initial condition of WRF by reducing the root-mean-square error and bias of PWV across 1200-1800 UTC, this also leads to an improvement in capturing nocturnal convection of mesoscale convective systems (MCSs; after 0300 UTC) and to an increase by 0.1mmh21 in subsequent precipitation during the 0300-0600 UTC period relative to no assimilation of the GPS-PWV(NODA) over the area with relatively more observation sites. This response is consistent with observed precipitation from the Integrated Multisatellite Retrievals for GPM Final Precipitation product. Moreover, compared to the NODA, we find that the GPS-PWVDAdecreases cloud-top temperature, increases most unstable convective available energy and surface dewpoint temperature, and thus creates a more favorable condition for convective organization in the region.
• Raman, A., Arellano, A. F., Delle Monache, L., Alessandrini, S., & Kumar, R. (2021). Exploring analog-based schemes for aerosol optical depth forecasting with WRF-Chem. Atmospheric Environment, 246(Issue). doi:10.1016/j.atmosenv.2020.118134
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  We implement and test an analog-based post-processing method to improve short range forecasts of aerosol optical depth (AOD) using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). Model postprocessing of AOD is performed using historical analog forecasts and a Kalman Filter (KF). Analog forecasts are selected from WRF-Chem simulations based on a set of environmental predictors (AOD, wind speed, precipitable water, and particulate matter) that exhibit past values similar to the current forecasts. Space-borne AOD from Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard Terra and Aqua satellites corresponding to the analogs are used to build the analog ensemble. This study focuses on a spatial domain covering the AERONET sites in contiguous United States. We use the analog ensemble weighted mean (AN) and Kalman filter analog (KFAN) algorithms, which are both trained using WRF-Chem AOD forecasts for the months of June to August during 2008–2011 and tested during the same months for 2012. Overall, the AOD forecast are more skillful when the forecast errors are corrected using a combination of analogs and Kalman filter in KFAN. This is especially true for the western US where the correlation of AOD with PM2.5, PM10, and surface horizontal wind speed are higher than those for other predictors. In fact, the overall biases in AOD are significantly reduced close to zero, with KFAN AOD being statistically indistinguishable to MODIS. However, both methods show mixed results (albeit still showing overall improvements) in eastern and central U.S., where AOD and its variability are highest. We find that, during the summer, PM is not the only predominant factor driving AOD in these regions, unlike western United States (U.S.) (except New Mexico and Arizona). We note, however, that the quality of the analogs depends on the model's capability to accurately simulate total precipitable water, which in turn influences aerosol sources and sinks.
• Raman, A., Arellano, A. F., Monache, L. D., Alessandrini, S., & Kumar, R. (2021). Exploring analog-based schemes for aerosol optical depth forecasting with WRF-Chem. Atmospheric Environment, 246, 118134.
• Risanto, C. B., Castro, C. L., Arellano, A. F., Moker, J. M., & Adams, D. K. (2021). The Impact of Assimilating GPS Precipitable Water Vapor in Convective-Permitting WRF-ARW on North American Monsoon Precipitation Forecasts over Northwest Mexico. Monthly Weather Review, 149(9), 3013 - 3035.
• Rose Lorenzo, G., Angela Bañaga, P., Obiminda Cambaliza, M., Templonuevo Cruz, M., Azadiaghdam, M., Arellano, A., Betito, G., Braun, R., Corral, A. F., Dadashazar, H., Edwards, E. L., Eloranta, E., Holz, R., Leung, G., Ma, L., Macdonald, A. B., Reid, J. S., Bernard Simpas, J., Stahl, C., , Marie Visaga, S., et al. (2021). Measurement report: Firework impacts on air quality in Metro Manila, Philippines, during the 2019 New Year revelry. Atmospheric Chemistry and Physics, 21(Issue 8). doi:10.5194/acp-21-6155-2021
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  Fireworks degrade air quality, reduce visibility, alter atmospheric chemistry, and cause short-term adverse health effects. However, there have not been any comprehensive physicochemical and optical measurements of fireworks and their associated impacts in a Southeast Asia megacity, where fireworks are a regular part of the culture. Sizeresolved particulate matter (PM) measurements were made before, during, and after New Year 2019 at the Manila Observatory in Quezon City, Philippines, as part of the Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex). A high-spectral-resolution lidar (HSRL) recorded a substantial increase in backscattered signal associated with high aerosol loading ∼ 440m above the surface during the peak of firework activities around 00:00 (local time). This was accompanied by PM2:5 concentrations peaking at 383.9 μgm-3. During the firework event, watersoluble ions and elements, which affect particle formation, growth, and fate, were mostly in the submicrometer diameter range. Total (>0:056 μm) water-soluble bulk particle mass concentrations were enriched by 5.7 times during the fireworks relative to the background (i.e., average of before and after the firework). The water-soluble mass fraction of PM2:5 increased by 18.5% above that of background values. This corresponded to increased volume fractions of inorganics which increased bulk particle hygroscopicity, kappa (κ), from 0.11 (background) to 0.18 (fireworks). Potassium and non-sea-salt (nss) SO2-4 contributed the most (70.9 %) to the water-soluble mass, with their mass size distributions shifting from a smaller to a larger submicrometer mode during the firework event. On the other hand, mass size distributions for NO3- , Cl-, and Mg2+ (21.1% mass contribution) shifted from a supermicrometer mode to a submicrometer mode. Being both uninfluenced by secondary aerosol formation and constituents of firework materials, a subset of species were identified as the best firework tracer species (Cu, Ba, Sr, K+, Al, and Pb). Although these species (excluding K+) only contributed 2.1% of the total mass concentration of watersoluble ions and elements, they exhibited the highest enrichments (6.1 to 65.2) during the fireworks. Surface microscopy analysis confirmed the presence of potassium/chloride-rich cubic particles along with capsule-shaped particles in firework samples. The results of this study highlight how firework emissions change the physicochemical and optical properties of water-soluble particles (e.g., mass size distribution, composition, hygroscopicity, and aerosol backscatter), which subsequently alters the background aerosol's respirability, influence on surroundings, ability to uptake gases, and viability as cloud condensation nuclei (CCN).
• Gaubert, B., Emmons, L. K., Raeder, K., Tilmes, S., Miyazaki, K., Arellano Jr., ,. A., Elguindi, N., Granier, C., Tang, W., Barr\'e, J., Worden, H. M., Buchholz, R. R., Edwards, D. P., Franke, P., Anderson, J. L., Saunois, M., Schroeder, J., Woo, J., Simpson, I. J., , Blake, D. R., et al. (2020). Correcting model biases of CO in East Asia: impact on oxidant distributions during KORUS-AQ. Atmospheric Chemistry and Physics, 20(23), 14617--14647.
• Gaubert, B., K. Emmons, L., Raeder, K., Tilmes, S., Miyazaki, K., F. Arellano, A., Elguindi, N., Granier, C., Tang, W., Barré, J., M. Worden, H., R. Buchholz, R., P. Edwards, D., Franke, P., L. Anderson, J., Saunois, M., Schroeder, J., Woo, J. H., J. Simpson, I., , R. Blake, D., et al. (2020). Correcting model biases of CO in East Asia: Impact on oxidant distributions during KORUS-AQ. Atmospheric Chemistry and Physics, 20(Issue 23). doi:10.5194/acp-20-14617-2020
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  Global coupled chemistry-climate models underestimate carbon monoxide (CO) in the Northern Hemisphere, exhibiting a pervasive negative bias against measurements peaking in late winter and early spring. While this bias has been commonly attributed to underestimation of direct anthropogenic and biomass burning emissions, chemical production and loss via OH reaction from emissions of anthropogenic and biogenic volatile organic compounds (VOCs) play an important role. Here we investigate the reasons for this underestimation using aircraft measurements taken in May and June 2016 from the Korea-United States Air Quality (KORUS-AQ) experiment in South Korea and the Air Chemistry Research in Asia (ARIAs) in the North China Plain (NCP). For reference, multispectral CO retrievals (V8J) from the Measurements of Pollution in the Troposphere (MOPITT) are jointly assimilated with meteorological observations using an ensemble adjustment Kalman filter (EAKF) within the global Community Atmosphere Model with Chemistry (CAM-Chem) and the Data Assimilation Research Testbed (DART). With regard to KORUS-AQ data, CO is underestimated by 42% in the control run and by 12% with the MOPITT assimilation run. The inversion suggests an underestimation of anthropogenic CO sources in many regions, by up to 80% for northern China, with large increments over the Liaoning Province and the North China Plain (NCP). Yet, an often-overlooked aspect of these inversions is that correcting the underestimation in anthropogenic CO emissions also improves the comparison with observational O3 datasets and observationally constrained box model simulations of OH and HO2. Running a CAM-Chem simulation with the updated emissions of anthropogenic CO reduces the bias by 29% for CO, 18% for ozone, 11% for HO2, and 27% for OH. Longer-lived anthropogenic VOCs whose model errors are correlated with CO are also improved, while short-lived VOCs, including formaldehyde, are difficult to constrain solely by assimilating satellite retrievals of CO. During an anticyclonic episode, better simulation of O3, with an average underestimation of 5.5ppbv, and a reduction in the bias of surface formaldehyde and oxygenated VOCs can be achieved by separately increasing by a factor of 2 the modeled biogenic emissions for the plant functional types found in Korea. Results also suggest that controlling VOC and CO emissions, in addition to widespread NOx controls, can improve ozone pollution over East Asia.
• Pfister, G. G., Eastham, S. D., Arellano, A. F., Aumont, B., Barsanti, K. C., Barth, M. C., Conley, A., Davis, N. A., Emmons, L. K., Fast, J. D., Fiore, A. M., Gaubert, B., Goldhaber, S., Granier, C., Grell, G. A., Guevara, M., Henze, D. K., Hodzic, A., Liu, X., , Marsh, D. R., et al. (2020). The Multi-Scale Infrastructure for Chemistry and Aerosols (MUSICA). Bulletin of the American Meteorological Society, 101(10), E1743 - E1760.
• Tang, W., Gaubert, B., Emmons, L., Choi, Y., DiGangi, J. P., Diskin, G. S., Xu, X., He, C., Worden, H., Tilmes, S., Buchholz, R., Halliday, H. S., & Arellano, A. F. (2020). On the relationship between tropospheric CO and CO$_2$ during KORUS-AQ and its role in constraining anthropogenic CO$_2$. Atmospheric Chemistry and Physics Discussions, 2020, 1--53.
• Arellano, A. F., Henze, D. K., & Saide, P. E. (2019). Data Assimilation and Inverse Modeling of the Atmospheric Composition II Posters. American Geophysical Union.
• Minjarez-Sosa, C. M., Fierro, L. M., Adams, D. K., Arellano, A. F., Moker, Jr., J. M., Castro, C. L., & Risanto, C. B. (2019). Evaluating Forecast Skills of Moisture from Convective-Permitting WRF-ARW Model during 2017 North American Monsoon Season. Atmosphere. doi:10.3390/atmos10110694
• Risanto, C. B., Castro, C. L., Moker, J. M., Arellano, A. F., Adams, D. K., Fierro, L. M., & Sosa, C. M. (2019). Evaluating forecast skills of moisture from convective-permitting WRF-ARW Model during 2017 North American Monsoon season. Atmosphere, 10(Issue 11). doi:10.3390/atmos10110694
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  This paper examines the ability of the Weather Research and Forecasting model forecast to simulate moisture and precipitation during the North American Monsoon GPS Hydrometeorological Network field campaign that took place in 2017. A convective-permitting model configuration performs daily weather forecast simulations for northwestern Mexico and southwestern United States. Model precipitable water vapor (PWV) exhibits wet biases greater than 0.5 mm at the initial forecast hour, and its diurnal cycle is out of phase with time, compared to observations. As a result, the model initiates and terminates precipitation earlier than the satellite and rain gauge measurements, underestimates the westward propagation of the convective systems, and exhibits relatively low forecast skills on the days where strong synoptic-scale forcing features are absent. Sensitivity analysis shows that model PWV in the domain is sensitive to changes in initial PWV at coastal sites, whereas the model precipitation and moisture flux convergence (QCONV) are sensitive to changes in initial PWV at the mountainous sites. Improving the initial physical states, such as PWV, potentially increases the forecast skills.
• Saide, P. E., Henze, D. K., & Arellano, A. F. (2019). Data Assimilation and Inverse Modeling of the Atmospheric Composition I. American Geophysical Union.
• Tang, W., Arellano, A. F., Gaubert, B., Miyazaki, K., & Worden, H. M. (2019). Satellite data reveal a common combustion emission pathway for major cities in China. Atmospheric Chemistry and Physics, 19(7), 4269--4288.
• Tang, W., Arellano, A. F., Gaubert, B., Miyazaki, K., & Worden, H. M. (2019). Satellite data reveal a common combustion emission pathway for major cities in China. Atmospheric Chemistry and Physics, 19(Issue 7). doi:10.5194/acp-19-4269-2019
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  Extensive fossil fuel combustion in rapidly developing cities severely affects air quality and public health.We report observational evidence of decadal changes in the efficiency and cleanness of bulk combustion over large cities in mainland China. In order to estimate the trends in enhancement ratios of CO and SO2 to NO2 (ΔCO/ΔNO2 and ΔSO2/ΔNO2) and infer emergent bulk combustion properties over these cities, we combine air quality retrievals from widely used satellite instruments across 2005-2014. We present results for four Chinese cities (Shenyang, Beijing, Shanghai, and Shenzhen) representing four levels of urban development. Our results show a robust coherent progression of declining to growing ΔCO/ΔNO2 relative to 2005 (-5.4±0.7 to +8.3±3.1%yr-1) and slowly declining ΔSO2/ΔNO2 (-6.0±1.0 to-3.4±1.0%yr-1) across the four cities. The coherent progression we find is not evident in the trends of emission ratios reported in Representative Concentration Pathway (RCP8.5) inventory. This progression is likely due to a shift towards cleaner combustion from industrial and residential sectors in Shanghai and Shenzhen that is not yet seen in Shenyang and Beijing. This overall trend is presently obfuscated by China's still relatively higher dependence on coal. Such progression is well-correlated with economic development and traces a common emission pathway that resembles evolution of air pollution in more developed cities. Our results highlight the utility of augmenting observing and modeling capabilities by exploiting enhancement ratios in constraining the time variation in emission ratios in current inventories. As cities and/or countries continue to socioeconomically develop, the ability to monitor combustion efficiency and effectiveness of pollution control becomes increasingly important in assessing sustainable control strategies.
• Tang, W., Emmons, L. K., Arellano Jr, ,., Gaubert, B., Knote, C., Tilmes, S., Buchholz, R. R., Pfister, G. G., Diskin, G. S., Blake, D. R., Blake, N. J., Meinardi, S., DiGangi, J. P., Choi, Y., Woo, J., He, C., Schroeder, J. R., Suh, I., Lee, H., , Jo, H., et al. (2019). Source Contributions to Carbon Monoxide Concentrations During KORUS-AQ Based on CAM-chem Model Applications. Journal of Geophysical Research: Atmospheres, 124(5), 2796-2822.
• Tang, W., Emmons, L. K., Arellano, A. F., Gaubert, B., Knote, C., Tilmes, S., Buchholz, R. R., Pfister, G. G., Diskin, G. S., Blake, D. R., Blake, N. J., Meinardi, S., DiGangi, J. P., Choi, Y., Woo, J. H., He, C., Schroeder, J. R., Suh, I., Lee, H. J., , Jo, H. Y., et al. (2019). Source Contributions to Carbon Monoxide Concentrations During KORUS-AQ Based on CAM-chem Model Applications. Journal of Geophysical Research: Atmospheres, 124(Issue 5). doi:10.1029/2018jd029151
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  We investigate regional sources contributing to CO during the Korea United States Air Quality (KORUS-AQ) campaign conducted over Korea (1 May to 10 June 2016) using 17 tagged CO simulations from the Community Atmosphere Model with chemistry (CAM-chem). The simulations use three spatial resolutions, three anthropogenic emission inventories, two meteorological fields, and nine emission scenarios. These simulations are evaluated against measurements from the DC-8 aircraft and Measurements Of Pollution In The Troposphere (MOPITT). Results show that simulations using bottom-up emissions are consistently lower (bias: −34 to −39%) and poorer performing (Taylor skill: 0.38–0.61) than simulations using alternative anthropogenic emissions (bias: −6 to −33%; Taylor skill: 0.48–0.86), particularly for enhanced Asian CO and volatile organic compound (VOC) emission scenarios, suggesting underestimation in modeled CO background and emissions in the region. The ranges of source contributions to modeled CO along DC-8 aircraft from Korea and southern (90°E to 123°E, 20°N to 29°N), middle (90°E to 123°E, 29°N to 38.5°N), and northern (90°E to 131.5°E, 38.5°N to 45°N) East Asia (EA) are 6–13%, ~5%, 16–28%, and 9–18%, respectively. CO emissions from middle and northern EA can reach Korea via transport within the boundary layer, whereas those from southern EA are transported to Korea mainly through the free troposphere. Emission contributions from middle EA dominate during continental outflow events (29–51%), while Korean emissions play an overall more important role for ground sites (up to 25–49%) and plumes within the boundary layer (up to 25–44%) in Korea. Finally, comparisons with four other source contribution approaches (FLEXPART 9.1 back trajectory calculations driven by Weather Research and Forecasting (WRF) WRF inert tracer, China signature VOCs, and CO to CO2 enhancement ratios) show general consistency with CAM-chem.
• Arellano, A. F. (2018). Exploring Multiple Constraints of Anthropogenic Pollution in Combustion Regions from Current Satellite Retrievals of Atmospheric Composition. American Geophysical Union.
• Edwards, D. P., Worden, H. M., Neil, D., Francis, G., Valle, T., & Arellano Jr., ,. A. (2018). The CHRONOS mission: capability for sub-hourly synoptic observations of carbon monoxide and methane to quantify emissions and transport of air pollution. Atmospheric Measurement Techniques, 11(2), 1061--1085.
• Edwards, D. P., Worden, H. M., Neil, D., Francis, G., Valle, T., & Arellano, A. F. (2018). The CHRONOS mission: Capability for sub-hourly synoptic observations of carbon monoxide and methane to quantify emissions and transport of air pollution. Atmospheric Measurement Techniques, 11(Issue 2). doi:10.5194/amt-11-1061-2018
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  The CHRONOS space mission concept provides time-resolved abundance for emissions and transport studies of the highly variable and highly uncertain air pollutants carbon monoxide and methane, with sub-hourly revisit rate at fine (-4 km) horizontal spatial resolution across a North American domain. CHRONOS can provide complete synoptic air pollution maps ("snapshots") of the continental domain with less than 10 min of observations. This rapid mapping enables visualization of air pollution transport simultaneously across the entire continent and enables a sentinel-like capability for monitoring evolving, or unanticipated, air pollution sources in multiple locations at the same time with high temporal resolution. CHRONOS uses a compact imaging gas filter correlation radiometer for these observations, with heritage from more than 17 years of scientific data and algorithm advances by the science teams for the Measurements of Pollution in the Troposphere (MOPITT) instrument on NASA's Terra spacecraft in low Earth orbit. To achieve continental-scale sub-hourly sampling, the CHRONOS mission would be conducted from geostationary orbit, with the instrument hosted on a communications or meteorological platform. CHRONOS observations would contribute to an integrated observing system for atmospheric composition using surface, suborbital and satellite data with atmospheric chemistry models, as defined by the Committee on Earth Observing Satellites. Addressing the U.S. National Academy's 2007 decadal survey direction to characterize diurnal changes in tropospheric composition, CHRONOS observations would find direct societal applications for air quality management and forecasting to protect public health.
• Fox, A. M., Hoar, T. J., Anderson, J. L., Arellano, A. F., Smith, W. K., Litvak, M. E., MacBean, N., Schimel, D. S., & Moore, D. J. (2018). Evaluation of a Data Assimilation System for Land Surface Models Using CLM4.5. Journal of Advances in Modeling Earth Systems, 10(Issue 10). doi:10.1029/2018ms001362
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  The magnitude and persistence of land carbon (C) pools influence long-term climate feedbacks. Interactive ecological processes influence land C pools and our understanding of these processes is imperfect so land surface models have errors and biases when compared to each other and to real observations. Here we implement an Ensemble Adjustment Kalman Filter (EAKF), a sequential state data assimilation technique to reduce these errors and biases. We implement the EAKF using the Data Assimilation Research Testbed coupled with the Community Land Model (CLM 4.5 in CESM 1.2). We assimilated simulated and real satellite observations for a site in central New Mexico, United States. A series of observing system simulation experiments allowed assessment of the data assimilation system without model error. This showed that assimilating biomass and leaf area index observations decreased model error in C dynamics forecasts (29% using biomass observations and 40% using leaf area index observations) and that assimilation in combination shows greater improvement (51% using both observation streams). Assimilating real observations highlighted likely model structural errors and we implemented an adaptive model-variance-inflation technique to allow the model to track the observations. Monthly and longer model forecasts using real observations were improved relative to forecasts without data assimilation. The reliable forecast lead-time varied by model pool and is dependent on how tightly the C pool is coupled to meteorologically driven processes. The EAKF and similar state data assimilation techniques could reduce errors in projections of the land C sink and provide more robust forecasts of C pools and land-atmosphere exchanges.
• Fox, A., Hoar, T., Anderson, J., Arellano, A. F., Smith, W., Litvak, M., MacBean, N., Schimel, D., & Moore, D. (2018). Evaluation of a Data Assimilation System for Land Surface Models using CLM4.5. Journal of Advances in Modeling Earth Systems.
• Granier, C., Arellano, A. F., & Stavrakou, J. (2018). The new Analysis of eMIssions usinG Observations (AMIGO) project of IGAC. IGACnews.
• Jiang, Z., McDonald, B. C., Worden, H., Worden, J. R., Miyazaki, K., Qu, Z., Henze, D. K., Jones, D. B., Arellano, A. F., Fischer, E. V., Zhu, L., & Folkert Boersma, K. (2018). Unexpected slowdown of US pollutant emission reduction in the past decade. Proceedings of the National Academy of Sciences of the United States of America, 115(Issue 20). doi:10.1073/pnas.1801191115
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  Ground and satellite observations show that air pollution regulations in the United States (US) have resulted in substantial reductions in emissions and corresponding improvements in air quality over the last several decades. However, large uncertainties remain in evaluating how recent regulations affect different emission sectors and pollutant trends. Here we show a significant slowdown in decreasing US emissions of nitrogen oxides (NOx) and carbon monoxide (CO) for 2011–2015 using satellite and surface measurements. This observed slowdown in emission reductions is significantly different from the trend expected using US Environmental Protection Agency (EPA) bottom-up inventories and impedes compliance with local and federal agency air-quality goals. We find that the difference between observations and EPA’s NOx emission estimates could be explained by: (i) growing relative contributions of industrial, area, and off-road sources, (ii) decreasing relative contributions of on-road gasoline, and (iii) slower than expected decreases in on-road diesel emissions.
• Jiang, Z., Worden, H., Worden, J., Miyazaki, K., McDonald, B., Qu, Z., Henze, D., Jones, D., Arellano, A. F., Fischer, E., Zhu, L., & Boersma, K. F. (2018). Unexpected slowdown of US pollutant emission reduction in the past decade. Proceedings of the National Academy of Sciences.
• Moker, J. M., Castro, C. L., Arellano, A. F., Serra, Y. L., & Adams, D. K. (2018). Convective-permitting hindcast simulations during the North American Monsoon GPS Transect Experiment 2013: Establishing baseline model performance without data assimilation. Journal of Applied Meteorology and Climatology, 57(Issue 8). doi:10.1175/jamc-d-17-0136.1
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  During the North American monsoon global positioning system (GPS) Transect Experiment 2013, daily convective-permitting WRF simulations are performed in northwestern Mexico and the southern Arizona border region using the operational Global Forecast System (GFS) and North American Mesoscale Forecast System (NAM) models as lateral boundary forcing and initial conditions. Compared to GPS precipitable water vapor (PWV), the WRF simulations display a consistent moist bias in the initial specification of PWV leading to convection beginning 3-6 h early. Given appreciable observed rainfall, days are classified as strongly and weakly forced based only on the presence of an inverted trough (IV); gulf surges did not noticeably impact the development of mesoscale convective systems (MCSs) and related convection in northwestern Mexico. Strongly forced days display higher modeled precipitation forecast skill than weakly forced days in the slopes of the northern Sierra Madre Occidental (SMO) away from the crest, especially toward the west where MCSs account for the greatest proportion of all monsoon-related precipitation. A case study spanning 8-10 July 2013 illustrates two consecutive days when nearly identical MCSs evolved over northern Sonora. Although a salient MCS is simulated on the strongly forced day (9-10 July 2013) when an IV is approaching the core monsoon region, a simulated MCS is basically nonexistent on the weakly forced day (8-9 July 2013) when the IV is farther away. The greater sensitivity to the initial specification of PWV in the weakly forced day suggests that assimilation of GPS-derived PWV for these types of days may be of greatest value in improving model precipitation forecasts.
• Moker, J., Castro, C., Serra, Y., Arellano, A. F., & Adams, D. (2018). Convective-permitting hindcast simulations during The North American Monsoon GPS Transect Experiment 2013: Establishing Baseline Model Performance Without Data Assimilation. Journal of Applied Meteorology and Climatology.
• Serr, Y. L., Haase, J. S., Adams, D. K., Fu, Q., Ackerman, T. P., Alexander, M. J., Arellano, A., Back, L., Emanuel, K., Kuang, Z., Mapes, B., Neelin, D., Raymond, D., Sobel, A. H., Staten, P. W., Subramanian, A., Thompson, D. W., Vecchi, G., Wood, R., & Zuidema, P. (2018). The risks of contr act ing the acquisition and processing of the nation's weather and climate data to the private sector. Bulletin of the American Meteorological Society, 99(Issue 5). doi:10.1175/bams-d-18-0034.1
• Serra, Y. L., Haase, J. S., Adams, D. K., Fu, Q., Ackerman, T. P., Alexander, M. J., Arellano, A., Back, L., Chen, S., Emanuel, K., Fuchs, Z., Kuang, Z., Mapes, B., Neelin, D., Raymond, D., Sobel, A. H., Staten, P. W., Subramanian, A., Thompson, D., , Vecchi, G., et al. (2018). The Risks of Contracting the Acquisition and Processing of the Nation’s Weather and Climate Data to the Private Sector. Bulletin of the American Meteorological Society, 99(5), 869-870.
• Tang, W., Arellano, A. F., DiGangi, J. P., Choi, Y., Diskin, G. S., Agust'i-Panareda, A., Parrington, M., Massart, S., Gaubert, B., Lee, Y., Kim, D., Jung, J., Hong, J., Hong, J., Kanaya, Y., Lee, M., Stauffer, R. M., Thompson, A. M., Flynn, J. H., & Woo, J. (2018). Evaluating High-Resolution Forecasts of Atmospheric CO and CO2 from a Global Prediction System during KORUS-AQ Field Campaign. Atmospheric Chemistry and Physics, 18(15), 11007-11030. doi:10.5194/acp-18-11007-2018
• Tang, W., Arellano, A. F., DiGangi, J. P., Choi, Y., Diskin, G. S., Agustí-Panareda, A., Parrington, M., Massart, S., Gaubert, B., Lee, Y., Kim, D., Jung, J., Hong, J., Hong, J. W., Kanaya, Y., Lee, M., Stauffer, R. M., Thompson, A. M., Flynn, J. H., & Woo, J. H. (2018). Evaluating high-resolution forecasts of atmospheric CO and CO2 from a global prediction system during KORUS-AQ field campaign. Atmospheric Chemistry and Physics, 18(Issue 15). doi:10.5194/acp-18-11007-2018
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  Accurate and consistent monitoring of anthropogenic combustion is imperative because of its significant health and environmental impacts, especially at city-to-regional scale. Here, we assess the performance of the Copernicus Atmosphere Monitoring Service (CAMS) global prediction system using measurements from aircraft, ground sites, and ships during the Korea-United States Air Quality (KORUS-AQ) field study in May to June 2016. Our evaluation focuses on CAMS CO and CO2 analyses as well as two higher-resolution forecasts (16 and 9km horizontal resolution) to assess their capability in predicting combustion signatures over east Asia. Our results show a slight overestimation of CAMS CO2 with a mean bias against airborne CO2 measurements of 2.2, 0.7, and 0.3ppmv for 16 and 9km CO2 forecasts, and analyses, respectively. The positive CO2 mean bias in the 16km forecast appears to be consistent across the vertical profile of the measurements. In contrast, we find a moderate underestimation of CAMS CO with an overall bias against airborne CO measurements of -19.2 (16km), -16.7 (9km), and -20.7ppbv (analysis). This negative CO mean bias is mostly seen below 750hPa for all three forecast/analysis configurations. Despite these biases, CAMS shows a remarkable agreement with observed enhancement ratios of CO with CO2 over the Seoul metropolitan area and over the West (Yellow) Sea, where east Asian outflows were sampled during the study period. More efficient combustion is observed over Seoul (dCO dCO2 Combining double low line 9ppbvppmv-1) compared to the West Sea (dCO dCO2 Combining double low line 28ppbvppmv-1). This "combustion signature contrast" is consistent with previous studies in these two regions. CAMS captured this difference in enhancement ratios (Seoul: 8-12ppbvppmv-1, the West Sea: ∼ 30ppbvppmv-1) regardless of forecast/analysis configurations. The correlation of CAMS CO bias with CO2 bias is relatively high over these two regions (Seoul: 0.64-0.90, the West Sea: ∼ 0.80) suggesting that the contrast captured by CAMS may be dominated by anthropogenic emission ratios used in CAMS. However, CAMS shows poorer performance in terms of capturing local-to-urban CO and CO2 variability. Along with measurements at ground sites over the Korean Peninsula, CAMS produces too high CO and CO2 concentrations at the surface with steeper vertical gradients (∼ 0.4ppmvhPa-1 for CO2 and 3.5ppbvhPa-1 for CO) in the morning samples than observed (∼ 0.25ppmvhPa-1 for CO2 and 1.7ppbvhPa-1 for CO), suggesting weaker boundary layer mixing in the model. Lastly, we find that the combination of CO analyses (i.e., improved initial condition) and use of finer resolution (9km vs. 16km) generally produces better forecasts.
• Tang, W., Arellano, A. F., Gaubert, B., Miyazaki, K., & Worden, H. M. (2018). Satellite Data Reveals a Common Combustion Emission Pathway for Major Cities in China. Atmospheric Chemistry and Physics Discussions, 2018, 1--27.
• Wespes, C., Hadji-lazaro, J., George, M., Clerbaux, C., Boynard, A., & Arellano, A. F. (2018). Emerging Patterns of O 3 Sensitivity to CO over Megacities Derived from Satellite Retrievals. The EGU General Assembly, 20.
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  The availability of long term multispecies retrievals offers an opportunity to study spatiotemporal patterns of atmo- spheric composition, especially over large anthropogenic pollution regions. Here, we jointly analyze IASI retrievals of O3 and CO (along with OMI NO2) to explore additional observational constraints on anthropogenic pollution. In particular, we estimate the trends of the enhancement ratios derived from IASI O3 and CO and OMI NO2 over major combustion regions in China and United States. Our results show intriguing differences of dO3/dCO across Chinese megacities. In particular, Beijing and Shenzhen shows a positive linear trend (0.58±2.15 and 0.38±0.42 %/yr respectively) while Shanghai shows a negative trend (-062±0.67%/yr). This may be attributed to differences in VOC-NOx-O3 regime between these cities, which predictive models of atmospheric composition should be able to capture. On the other hand, enhancements of O3 derived from these ratios show a pattern of decreasing to increasing trend across Beijing, Shanghai, and Shenzhen which may indicate differences in combustion-related activity between these cities consistent with the developing economic status of these cities. We suggest further evaluation against other datasets (ground- based, airborne, or other retrievals) to enhance the rigor of these find- ings. Nevertheless, this study offers an impetus towards characterizing other species relationships (e.g., IASI NH3, CH4, CO2) not only as basis for monitoring consistency in atmospheric composition but also as a way to fully utilize the information content of these retrieval products in the context of data assimilation and reanalysis.
• tang, W., Emmons, L., Arellano, A. F., Gaubert, B., Knote, C., Tilmes, S., Buchholz, R., Pfister, G., Diskin, G., Blake, D., Blake, N., DiGangi, J., & Choi, Y. (2018). Source Contribution to Carbon Monoxide during KORUS-AQ Using CAM-Chem Tagged Tracers. Journal of Geophysical Research.
• Arellano, A. F., & Raman, A. (2017). Spatial and Temporal Variations in Characteristic Ratios of Elemental Carbon to Carbon Monoxide and Nitrogen Oxides across the United States. Environmental Science & Technology, 51(12), 6829-6838. doi:10.1021/acs.est.7b00161
• Arellano, A. F., Gaubert, B., Worden, H. M., Emmons, L. K., Tilmes, S., Barré, J., Martinez Alonso, S., Vitt, F., Anderson, J. L., Alkemade, F., Houweling, S., & Edwards, D. P. (2017). Chemical Feedback From Decreasing Carbon Monoxide Emissions. Geophysical Research Letters, 44(19), 9985-9995. doi:10.1002/2017gl074987
• Edwards, D., Worden, H., Neil, D., Francis, G., Valle, T., & Arellano, A. F. (2017). The CHRONOS mission: Capability for sub-hourly synoptic observations of carbon monoxide and methane to quantify emissions and transport of air pollution. Atmospheric Measurement Techniques Discussions. doi:https://doi.org/10.5194/amt-2017-194
• Gaubert, B., Worden, H. M., Arellano, A. F., Emmons, L. K., Tilmes, S., Barre, J., Martinez-Alonso, S., Vitt, F., Anderson, J. L., & Edwards, D. P. (2017). Chemical feedback from decreasing carbon monoxide emissions. Geophysical Research Letters.
• Jiang, Z., Worden, H., Worden, J. R., Henze, D. K., Jones, D., Arellano, A. F., Fischer, E. V., Zhu, L., Miyazaki, K., Boersma, K. F., & Payne, V. H. (2017). Inconsistent decadal variations between surface and free tropospheric nitrogen oxides over United States. Atmospheric Chemistry and Physics Discussions, 2017, 1--27.
• Jiang, Z., Worden, J., Worden, H., Deeter, M., Jones, D., & Arellano, A. F. (2017). Fifteen year CO emission estimates constrained with MOPITT CO measurements. Atmospheric Chemistry and Physics.
• Montan'e, F., Fox, A. M., Arellano, A. F., MacBean, N., Alexander, M. R., Dye, A., Bishop, D. A., Trouet, V., Babst, F., Hessl, A. E., Pederson, N., Blanken, P. D., Bohrer, G., Gough, C. M., Litvak, M. E., Novick, K. A., Phillips, R. P., Wood, J. D., & Moore, D. (2017). Evaluating the effect of alternative carbon allocation schemes in a land surface model~(CLM4.5) on carbon fluxes, pools, and turnover in temperate forests. Geoscientific Model Development, 10(9), 3499--3517.
• Montané, F., Fox, A. M., Arellano, A. F., MacBean, N., Ross Alexander, M., Dye, A., Bishop, D. A., Trouet, V., Babst, F., Hessl, A. E., Pederson, N., Blanken, P. D., Bohrer, G., Gough, C. M., Litvak, M. E., Novick, K. A., Phillips, R. P., Wood, J. D., & Moore, D. J. (2017). Evaluating the effect of alternative carbon allocation schemes in a land surface model (CLM4.5) on carbon fluxes, pools, and turnover in temperate forests. Geoscientific Model Development, 10(Issue 9). doi:10.5194/gmd-10-3499-2017
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  How carbon (C) is allocated to different plant tissues (leaves, stem, and roots) determines how long C remains in plant biomass and thus remains a central challenge for understanding the global C cycle. We used a diverse set of observations (AmeriFlux eddy covariance tower observations, biomass estimates from tree-ring data, and leaf area index (LAI) measurements) to compare C fluxes, pools, and LAI data with those predicted by a land surface model (LSM), the Community Land Model (CLM4.5). We ran CLM4.5 for nine temperate (including evergreen and deciduous) forests in North America between 1980 and 2013 using four different C allocation schemes: dynamic C allocation scheme (named "D-CLM4.5") with one dynamic allometric parameter, which allocates C to the stem and leaves to vary in time as a function of annual net primary production (NPP); ii. an alternative dynamic C allocation scheme (named "DLitton"), where, similar to (i), C allocation is a dynamic function of annual NPP, but unlike (i) includes two dynamic allometric parameters involving allocation to leaves, stem, and coarse roots; iii.-iv. a fixed C allocation scheme with two variants, one representative of observations in evergreen (named "F Evergreen") and the other of observations in deciduous forests (named "F-Deciduous"). D-CLM4.5 generally overestimated gross primary production (GPP) and ecosystem respiration, and underestimated net ecosystem exchange (NEE). In D-CLM4.5, initial aboveground biomass in 1980 was largely overestimated (between 10 527 and 12 897 g Cm-2) for deciduous forests, whereas aboveground biomass accumulation through time (between 1980 and 2011) was highly underestimated (between 1222 and 7557 gCm-2) for both evergreen and deciduous sites due to a lower stem turnover rate in the sites than the one used in the model. D-CLM4.5 overestimated LAI in both evergreen and deciduous sites because the leaf C-LAI relationship in the model did not match the observed leaf C- LAI relationship at our sites. Although the four C allocation schemes gave similar results for aggregated C fluxes, they translated to important differences in long-term aboveground biomass accumulation and aboveground NPP. For deciduous forests, D-Litton gave more realistic Cstem - Cleaf ratios and strongly reduced the overestimation of initial aboveground biomass and aboveground NPP for deciduous forests by D-CLM4.5. We identified key structural and parameterization deficits that need refinement to improve the accuracy of LSMs in the near future. These include changing how C is allocated in fixed and dynamic schemes based on data from current forest syntheses and different parameterization of allocation schemes for different forest types.Our results highlight the utility of using measurements of aboveground biomass to evaluate and constrain the C allocation scheme in LSMs, and suggest that stem turnover is overestimated by CLM4.5 for these AmeriFlux sites. Understanding the controls of turnover will be critical to improving long-term C processes in LSMs.
• Raman, A., & Arellano, A. F. (2017). Characteristic ratios of black carbon with carbon monoxide and nitrogen oxides across the United States. Environmental Science and Technology.
• Silva, S. J., & Arellano, A. F. (2017). Characterizing Regional-Scale Combustion Using Satellite Retrievals of CO, NO2 and CO2. Remote Sensing, 9(Issue 7). doi:10.3390/rs9070744
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  We present joint analyses of satellite-observed combustion products to examine bulk characteristics of combustion in megacities and fire regions. We use retrievals of CO, NO2 and CO2 from NASA/Terra Measurement of Pollution In The Troposphere, NASA/Aura Ozone Monitoring Instrument, and JAXA Greenhouse Gases Observing Satellite to estimate atmospheric enhancements of these co-emitted species based on their spatiotemporal variability (spread, σ) within 14 regions dominated by combustion emissions. We find that patterns in σXCO/σXCO2 and σXCO/σXNO2 are able to distinguish between combustion types across the globe. These patterns show distinct groupings for biomass burning and the developing/developed status of a region that are not well represented in global emissions inventories. We show here that such multi-species analyses can provide constraints on emission inventories, and be useful in monitoring trends and understanding regional-scale combustion.
• Silva, S. J., & Arellano, A. F. (2017). Characterizing regional-scale combustion using satellite retrievals of CO, NO2, and CO2. Remote Sensing, 9(7). doi:doi:10.3390/rs9070744
• Tang, W., & Arellano, A. F. (2017). Investigating dominant characteristics of fires across the Amazon during 2005–2014 through satellite data synthesis of combustion signatures. Journal of Geophysical Research, 122(Issue 2).
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  Estimates of fire emissions remain uncertain due to limited constraints on the variations in fire characteristics. Here we demonstrate the utility of space-based observations of smoke constituents in addressing this limitation. We introduce a satellite-derived smoke index (SI) as an indicator of the dominant phase of large-scale fires. This index is calculated as the ratio of the geometric mean of observed fractional enhancements (due to fire) in carbon monoxide and aerosol optical depth to that of nitrogen dioxide. We assess the usefulness of this index on fires in the Amazon. We analyze the seasonal, regional, and interannual joint distribution of SI and fire radiative power (FRP) in relation to fire hotspots, land cover, Drought Severity Index, and deforestation rate estimates. We also compare this index with an analogous quantity derived from field data or emission inventories. Our results show that SI changes from low (more flaming) to high (more smoldering) during the course of a fire season, which is consistent with the changes in observed maximum FRPs from high to low. We also find that flaming combustion is more dominant in areas where deforestation fires dominate, while smoldering combustion has a larger influence during drought years when understory fires are more likely enhanced. Lastly, we find that the spatiotemporal variation in SI is inconsistent with current emission inventories. Although we recognize some limitations of this approach, our results point to the utility of SI as a proxy for overall combustion efficiency in the parameterization of fire emission models.
• Arellano, A. F. (2016). Assimilating compact phase space retrievals of atmospheric composition with WRF-Chem/DART: a regional chemical transport/ensemble Kalman filter data assimilation system. Geoscientific Model Development, 9(3), 965-978. doi:10.5194/gmd-9-965-2016
• Barre, J., Edwards, D., Worden, H., Arellano, A. F., Gaubert, B., daSilva, A., Lahoz, W., & Anderson, J. (2016). On the feasibility of monitoring carbon monoxide in the lower troposphere from a constellation of Northern Hemisphere geostationary satellites: Part II. Atmospheric Environment.
• Barré, J., Edwards, D., Worden, H., Arellano, A., Gaubert, B., Da Silva, A., Lahoz, W., & Anderson, J. (2016). On the feasibility of monitoring carbon monoxide in the lower troposphere from a constellation of northern hemisphere geostationary satellites: Global scale assimilation experiments (Part II). Atmospheric Environment, 140(Issue). doi:10.1016/j.atmosenv.2016.06.001
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  This paper describes the second phase of an Observing System Simulation Experiment (OSSE) that utilizes the synthetic measurements from a constellation of satellites measuring atmospheric composition from geostationary (GEO) Earth orbit presented in part I of the study. Our OSSE is focused on carbon monoxide observations over North America, East Asia and Europe where most of the anthropogenic sources are located. Here we assess the impact of a potential GEO constellation on constraining northern hemisphere (NH) carbon monoxide (CO) using data assimilation. We show how cloud cover affects the GEO constellation data density with the largest cloud cover (i.e., lowest data density) occurring during Asian summer. We compare the modeled state of the atmosphere (Control Run), before CO data assimilation, with the known “true” state of the atmosphere (Nature Run) and show that our setup provides realistic atmospheric CO fields and emission budgets. Overall, the Control Run underestimates CO concentrations in the northern hemisphere, especially in areas close to CO sources. Assimilation experiments show that constraining CO close to the main anthropogenic sources significantly reduces errors in NH CO compared to the Control Run. We assess the changes in error reduction when only single satellite instruments are available as compared to the full constellation. We find large differences in how measurements for each continental scale observation system affect the hemispherical improvement in long-range transport patterns, especially due to seasonal cloud cover. A GEO constellation will provide the most efficient constraint on NH CO during winter when CO lifetime is longer and increments from data assimilation associated with source regions are advected further around the globe.
• Gaubert, B., Arellano, A. F., Barre, J., Worden, H., Emmons, L., Tilmes, S., Buchholz, R., Wiedinmyer, C., Martinez-Alonso, S., Raeder, K., Collins, N., Anderson, J., Vitt, F., Edwards, D., Andreae, M., Hannigan, J., Petri, C., Strong, K., & Jones, N. (2016). Towards a chemical reanalysis in a coupled chemistry-climate model: An evaluation of MOPITT CO assimilation and its impact on tropospheric composition. Journal of Geophysical Research.
• Gaubert, B., Arellano, A. F., Barré, J., Worden, H. M., Emmons, L. K., Tilmes, S., Buchholz, R. R., Vitt, F., Raeder, K., Collins, N., Anderson, J. L., Wiedinmyer, C., Martinez Alonso, S., Edwards, D. P., Andreae, M. O., Hannigan, J. W., Petri, C., Strong, K., & Jones, N. (2016). Toward a chemical reanalysis in a coupled chemistry-climate model: An evaluation of MOPITT CO assimilation and its impact on tropospheric composition. Journal of Geophysical Research, 121(Issue 12). doi:10.1002/2016jd024863
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  We examine in detail a 1 year global reanalysis of carbon monoxide (CO) that is based on joint assimilation of conventional meteorological observations and Measurement of Pollution in The Troposphere (MOPITT) multispectral CO retrievals in the Community Earth System Model (CESM). Our focus is to assess the impact to the chemical system when CO distribution is constrained in a coupled full chemistry-climate model like CESM. To do this, we first evaluate the joint reanalysis (MOPITT Reanalysis) against four sets of independent observations and compare its performance against a reanalysis with no MOPITT assimilation (Control Run). We then investigate the CO burden and chemical response with the aid of tagged sectoral CO tracers.We estimate the total tropospheric CO burden in 2002 (from ensemble mean and spread) to be 371 ± 12%Tg for MOPITT Reanalysis and 291 ± 9%Tg for Control Run. Our multispecies analysis of this difference suggests that (a) direct emissions of CO and hydrocarbons are too low in the inventory used in this study and (b) chemical oxidation, transport, and deposition processes are not accurately and consistently represented in the model. Increases in CO led to net reduction of OH and subsequent longer lifetime of CH4 (Control Run: 8.7 years versus MOPITT Reanalysis: 9.3 years). Yet at the same time, this increase led to 5-10% enhancement of Northern Hemisphere O3 and overall photochemical activity via HOx recycling. Such nonlinear effects further complicate the attribution to uncertainties in direct emissions alone. This has implications to chemistry-climate modeling and inversion studies of longer-lived species.
• Lopez, D. H., Rabbani, M. R., Crosbie, E., Raman, A., Arellano, A. F., & Sorooshian, A. (2016). Frequency and character of extreme aerosol events in the Southwestern United States: A case study analysis in Arizona. Atmosphere, 7(Issue 1). doi:10.3390/atmos7010001
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  This study uses more than a decade's worth of data across Arizona to characterize the spatiotemporal distribution, frequency, and source of extreme aerosol events, defined as when the concentration of a species on a particular day exceeds that of the average plus two standard deviations for that given month. Depending on which of eight sites studied, between 5% and 7% of the total days exhibited an extreme aerosol event due to either extreme levels of PM10, PM2.5, and/or fine soil. Grand Canyon exhibited the most extreme event days (120, i.e., 7% of its total days). Fine soil is the pollutant type that most frequently impacted multiple sites at once at an extreme level. PM10, PM2.5, fine soil, non-Asian dust, and Elemental Carbon extreme events occurred most frequently in August. Nearly all Asian dust extreme events occurred between March and June. Extreme Elemental Carbon events have decreased as a function of time with statistical significance, while other pollutant categories did not show any significant change. Extreme events were most frequent for the various pollutant categories on either Wednesday or Thursday, but there was no statistically significant difference in the number of events on any particular day or on weekends versus weekdays.
• Mizzi, A. P., Arellano, A. F., Edwards, D. P., Anderson, J. L., & Pfister, G. G. (2016). Assimilating compact phase space retrievals of atmospheric composition with WRF-Chem/DART: A regional chemical transport/ensemble Kalman filter data assimilation system. Geoscientific Model Development, 9(Issue 3). doi:10.5194/gmd-9-965-2016
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  This paper introduces the Weather Research and Forecasting Model with chemistry/Data Assimilation Research Testbed (WRF-Chem/DART) chemical transport forecasting/data assimilation system together with the assimilation of compact phase space retrievals of satellite-derived atmospheric composition products. WRF-Chem is a state-of-the-art chemical transport model. DART is a flexible software environment for researching ensemble data assimilation with different assimilation and forecast model options. DART's primary assimilation tool is the ensemble adjustment Kalman filter. WRF-Chem/DART is applied to the assimilation of Terra/Measurement of Pollution in the Troposphere (MOPITT) carbon monoxide (CO) trace gas retrieval profiles. Those CO observations are first assimilated as quasi-optimal retrievals (QORs). Our results show that assimilation of the CO retrievals (i) reduced WRF-Chem's CO bias in retrieval and state space, and (ii) improved the CO forecast skill by reducing the Root Mean Square Error (RMSE) and increasing the Coefficient of Determination (R2). Those CO forecast improvements were significant at the 95 % level. Trace gas retrieval data sets contain (i) large amounts of data with limited information content per observation, (ii) error covariance cross-correlations, and (iii) contributions from the retrieval prior profile that should be removed before assimilation. Those characteristics present challenges to the assimilation of retrievals. This paper addresses those challenges by introducing the assimilation of compact phase space retrievals (CPSRs). CPSRs are obtained by preprocessing retrieval data sets with an algorithm that (i) compresses the retrieval data, (ii) diagonalizes the error covariance, and (iii) removes the retrieval prior profile contribution. Most modern ensemble assimilation algorithms can efficiently assimilate CPSRs. Our results show that assimilation of MOPITT CO CPSRs reduced the number of observations (and assimilation computation costs) by g 1/4 g ¯35 %, while providing CO forecast improvements comparable to or better than with the assimilation of MOPITT CO QORs.
• Raman, A., Arellano, A. F., & Sorooshian, A. (2016). Decreasing Aerosol Loading in the North American Monsoon Region. Atmosphere, 7(2). doi:10.3390/atmos7020024
• Raman, A., Arellano, A. F., & Sorooshian, A. (2016). Decreasing aerosol loading in the north American monsoon region. Atmosphere, 7(Issue 2). doi:10.3390/atmos7020024
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  We examine the spatio-temporal variability of aerosol loading in the recent decade (2005-2014) over the North American Monsoon (NAM) region. Emerging patterns are characterized using aerosol optical depth (AOD) retrievals from the NASA Terra/Moderate Resolution Imaging Spectroradiometer (MODIS) instrument along with a suite of satellite retrievals of atmospheric and land-surface properties. We selected 20 aerosol hotspots and classified them into fire, anthropogenic, dust, and NAM alley clusters based on the dominant driver influencing aerosol variability. We then analyzed multivariate statistics of associated anomalies during pre-, monsoon, and post-monsoon periods. Our results show a decrease in aerosol loading for the entire NAM region, confirming previous reports of a declining AOD trend over the continental United States. This is evident during pre-monsoon and monsoon for fire and anthropogenic clusters, which are associated with a decrease in the lower and upper quartile of fire counts and carbon monoxide, respectively. The overall pattern is obfuscated in the NAM alley, especially during monsoon and post-monsoon seasons. While the NAM alley is mostly affected by monsoon precipitation, the frequent occurrence of dust storms in the area modulates this trend. We find that aerosol loading in the dust cluster is associated with observed vegetation index and has only slightly decreased in the recent decade.
• Serra, Y. L., Adams, D. K., Minjarez-Sosa, C., Moker, J. M., Arellano, A. F., Castro, C. L., Quintanar, A. I., Alatorre, L., Granados, A., Vazquez, G. E., Holub, K., & DeMets, C. (2016). The north American monsoon GPS transect experiment 2013. Bulletin of the American Meteorological Society, 97(Issue 11). doi:10.1175/bams-d-14-00250.1
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  Expanding networks of all-weather, high-time-resolution GPS networks with surface meteorology throughout the southwestern United States and Mexico offers opportunities for improved understanding of the North American monsoon convection and forecasting of organized convective events and associated hazards.
• Serra, Y., Adams, D., Minjares-Sosa, C., Castro, C., Moker, J., Arellano, A. F., Quintanar, A., Alatorre, L., Granados, A., Vasqueze, E., Holub, K., & DeMets, C. (2016). The North American Monsoon GPS Transect Experiment 2013. Bulletin of the American Meteorological Society.
• Tang, W., & Arellano, A. F. (2017). Investigating the dominant characteristics of fires across the Amazon during 2005–2014 through satellite data synthesis of combustion signatures. Journal of Geophysical Research.
• Worden, J. R., Worden, H. M., Jones, D. B., Jiang, Z., Henze, D. K., Deeter, M. N., & Arellano, A. F. (2016). A 15-year record of CO emissions constrained by MOPITT CO observations. Atmospheric Chemistry and Physics, 17(7), 4565-4583. doi:10.5194/acp-17-4565-2017
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  Abstract. Long-term measurements from satellites and surface stations have demonstrated a decreasing trend of tropospheric carbon monoxide (CO) in the Northern Hemisphere over the past decade. Likely explanations for this decrease include changes in anthropogenic, fires, and/or biogenic emissions or changes in the primary chemical sink hydroxyl radical (OH). Using remotely sensed CO measurements from the Measurement of Pollution in the Troposphere (MOPITT) satellite instrument, in situ methyl chloroform (MCF) measurements from the World Data Centre for Greenhouse Gases (WDCGG) and the adjoint of the GEOS-Chem model, we estimate the change in global CO emissions from 2001 to 2015. We show that the loss rate of MCF varied by 0.2 % in the past 15 years, indicating that changes in global OH distributions do not explain the recent decrease in CO. Our two-step inversion approach for estimating CO emissions is intended to mitigate the effect of bias errors in the MOPITT data as well as model errors in transport and chemistry, which are the primary factors contributing to the uncertainties when quantifying CO emissions using these remotely sensed data. Our results confirm that the decreasing trend of tropospheric CO in the Northern Hemisphere is due to decreasing CO emissions from anthropogenic and biomass burning sources. In particular, we find decreasing CO emissions from the United States and China in the past 15 years, and unchanged anthropogenic CO emissions from Europe since 2008. We find decreasing trends of biomass burning CO emissions from boreal North America, boreal Asia and South America, but little change over Africa. In contrast to prior results, we find that a positive trend in CO emissions is likely for India and southeast Asia.
• Adams, D. K., Fernandes, R. M., Holub, K. L., Gutman, S. I., Barbosa, H. M., Machado, L. A., Calhlheiros, A. J., Bennett, R. A., Kursinski, E. R., Sapucci, L. F., DeMets, C., Chagas, G. F., Arellano, A., Filizola, N., Rocha, A. A., Silva, R. A., Assuncao, L. M., Cirino, G. G., Pauliquevis, T., , Portela, B. T., et al. (2015). THE AMAZON DENSE GNSS METEOROLOGICAL NETWORK A New Approach for Examining Water Vapor and Deep Convection Interactions in the Tropics. BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, 96(12), 2151-2165.
• Arellano, A. F. (2015). Data Assimilation and Inverse Modeling for Atmospheric Composition Applications I. American Geophysical Union.
• Arellano, A. F. (2015). Inverse Modeling of BC and CO Sources in WRF-Chem. NCAR.
• Arellano, A. F. (2015). The characteristics of tropospheric CO2 retrieved by AIRS, GOSAT and IASI in East Asia. Disaster Advances, 8(9), 1-13.
• Barre, J., Edwards, D. P., Gaubert, B., Worden, H. M., Arellano, A. F., & Anderson, J. L. (2015). Carbon Monoxide Data Assimilation for Atmospheric Composition and Climate Science: Evaluating Performance with Current and Future Observations. American Geophysical Union.
• Barre, J., Gaubert, B., Arellano, A. F., Worden, H. M., Edwards, D. P., Deeter, M. N., Anderson, J. L., Raeder, K., Collins, N., Tilmes, S., Francois, G., Clerbaux, C., Emmons, L. K., Pfister, G. G., Coheur, P., & Hurtmans, D. (2015). Assessing the impacts of assimilating IASI and MOPITT CO retrievals using CESM-CAM-chem and DART. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 120(19).
• Barré, J., Gaubert, B., Arellano, A. F., Worden, H. M., Edwards, D. P., Deeter, M. N., Anderson, J. L., Raeder, K., Collins, N., Tilmes, S., Francis, G., Clerbaux, C., Emmons, L. K., Pfister, G. G., Coheur, P., & Hurtmans, D. (2015). Assessing the impacts of assimilating IASI and MOPITT CO retrievals using CESM‐CAM‐chem and DART. Journal of Geophysical Research: Atmospheres, 120(19). doi:10.1002/2015jd023467
• Gaubert, B., Arellano, A. F., Barre, J., Worden, H. M., Emmons, L., Tilmes, S., Buchholz, R. R., Wiedinmyer, C., Vitt, F., Anderson, J. L., Deeter, M. N., & Edwards, D. P. (2015). Chemical Response of CESM/CAM-Chem to MOPITT CO Ensemble-based Chemical Data Assimilation. American Geophysical Union.
• Knote, C., Barre, J., Eckl, M., Hornbrook, R. S., Wiedinmyer, C., Emmons, L., Orlando, J. J., Tyndall, G. S., & Arellano, A. F. (2015). Inferring the unobserved chemical state of the atmosphere: idealized data assimilation experiments. American Geophysical Union.
• Mizzi, A., Arellano, A. F., Edwards, D. P., Anderson, J. L., & Pfister, G. G. (2015). Assimilating Compact Phase Space Retrievals of Atmospheric Composition with WRF-Chem/DART: A Regional Chemical Transport/Ensemble Kalman Filter Data Assimilation System. Geoscientific Model Development Discussion. doi:10.5194/gmdd-8-1-2015
• Montane, F., Arellano, A. F., Scaven, V. L., Moore, D. J., Fox, A. M., Arellano, A. F., & Alexander, M. R. (2015). Comparing Different Model Structures for Carbon Allocation in the Community Land Model (CLM). American Geophysical Union.
• Moon, Y. S., & Arellano, A. F. (2015). The characteristics of tropospheric CO2 retrieved by AIRS, GOSAT and IASI in East Asia. Disaster Advances, 8(9), 1-13.
• Moon, Y. S., & Arellano, A. F. (2015). The characteristics of tropospheric CO2 retrieved by AIRS, GOSAT and IASI in East Asia. Disaster Advances, 8(Issue 9).
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  AIRS, GOSAT and IASI satellite data were validated to analyze the temporal and spatial distribution of the mid-tropospheric carbon dioxide (CO2) concentration in East Asia. The mid-Atmospheric retrieval data of GOSAT was reflected in the seasonal characteristics with the correlation coefficient of 0.94 in comparison with the ground-based CO2 data at Anmyeondo in Korea during the period of a year in 2011, On the other hand, the correlation coefficient between the AIRS data and the Anmyeondo data was 0.4 but the RMSE was the minimum in 4.46 among them. In addition, the AIRS data were compared by the groundbased data measured at Mauna Loa in USA, Waliguan in China and Ryori in Japan and Anmyeondo in Korea for the periods of 9 years from 2003 to 2011. The ground-based CO2 concentrationdata of Mauna Loa located at the highest elevation was in the high correlation coefficient of 0.95 in comparison with the AIRS data and those of Waliguan, Ryori and Anmyeondo were seen in 0.82, 0.78 and 0.69 respectively. The mid-tropospheric CO2 concentration from 375 ppm to 390ppm during the period of 2003 through 2010 at Mauna Loa and Waliguan was in that of the global background on the 700 hPa surface. The ground-based CO2 concentration from 375ppm to 395ppm during the period at Anmyeondo was in agreement with that of Ryori similar to the meteorological characteristics such as back trajectories and atmospheric stability. However, the mid-tropospheric CO2 concentrations between Anmyeondo and Ryori were affected by meteorological conditions such as atmospheric vorticity and wind speed on 700 hPa. Furthermore, the higher mid-tropospheric CO2 concentration zone, a dominant transport pathway, was in 30 o N to 60 o N range during the period from 2003 to 2011. The enhancement CO2 concentration levels were in dry areas such as Gobbi, Mongolian and Manchuria deserts in East Asia which were related to the longrange transport, CO2 emissions by human activities and sinking from photosynthesis along with the strong westerly wind zone.
• Raman, A., & Arellano, A. F. (2015). Using Combustion Tracers to Estimate Surface Black Carbon Distributions in WRF-Chem. American Geophysical Union.
• Arellano, A. F. (2014). Constraints on Local-­to-­Regional Anthropogenic CO2 from Satellite Retrievals of Combustion-­related Trace Gases: Initial Assessment Using Observing System Simulation Experiments (OSSEs). American Geophysical Union.
• Barre, J., Worden, H. M., Mizzi, A. P., Gaubert, B., Edwards, D. P., Arellano, A. F., & Anderson, J. L. (2014). Assessment of IASI CO and MOPITT CO Data Assimilation in CAM-Chem.. Journal of Geophysical Research.
• Edwards, D. P., Worden, H. M., Mizzi, A. P., Lahoz, W., Gaubert, B., Barre, J., Arellano, A. F., & Anderson, J. L. (2014). The atmospheric composition geostationary satellite constellation for air quality and climate science: Evaluating performance with Observation System Simulation Experiments. CEOS.
• Liu, Y., Liu, Y., Matthes, J. H., Moore, D. J., Dietze, M. C., Arellano, A. F., Arellano, A. F., Dawson, A., Fox, A. M., Goring, S., Mclachlan, J. S., Montane, F., Moreno, G., Poulter, B., Quaife, T., Ricciuto, D. M., Schaefer, K., Steinkamp, J., Williams, J. W., , Williams, J. W., et al. (2014). Assessing the long-term performance of terrestrial ecosystem models in northeastern United States: linking model structure and output. American Geophysical Union.
• Prabhakar, G., Sorooshian, A., Toffol, E., Arellano, A. F., & Betterton, E. A. (2014). Spatiotemporal distribution of airborne particulate metals and metalloids in a populated arid region. Atmospheric Environment, 92(Issue). doi:10.1016/j.atmosenv.2014.04.044
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  A statistical analysis of data from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network of aerosol samplers has been used to study the spatial and temporal concentration trends in airborne particulate metals and metalloids for southern Arizona. The study region is a rapidly growing area in southwestern North America characterized by high fine soil concentrations (among the highest in the United States), anthropogenic emissions from an area within the fastest growing region in the United States, and a high density of active and abandoned mining sites. Crustal tracers in the region are most abundant in the summer (April-June) followed by fall (October-November) as a result of dry meteorological conditions which favor dust emissions from natural and anthropogenic activity. A distinct day-of-week cycle is evident for crustal tracer mass concentrations, with the greatest amplitude evident in urban areas. There have been significant reductions since 1988 in the concentrations of toxic species that are typically associated with smelting and mining. Periods with high fine soil concentrations coincide with higher concentrations of metals and metalloids in the atmosphere, with the enhancement being higher at urban sites. © 2014 Elsevier Ltd.
• Raman, A., Arellano Jr., A. F., & Brost, J. J. (2014). Revisiting haboobs in the southwestern United States: An observational case study of the 5 July 2011 Phoenix dust storm. Atmospheric Environment, 89, 179-188.
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  Abstract:Convectively-driven dust storms (or haboobs) are common phenomena in the southwestern United States. However, studies about haboobs in this region are limited. Here, we investigate the state and fate of a massive haboob that hit Phoenix, Arizona on 5 July 2011 using satellite, radar, and ground-based observations. This haboob was a result of strong outflow boundaries (with peak wind gusts of 29ms-1) from storms that were initiated in the southeast of Tucson. In particular, we find three major outflow systems (based on radar data) that were generated by forward propagating storms, ultimately merging near Phoenix. This resulted in peak hourly PM10 and PM2.5 concentrations of 1974μgm-3 and 907μgm-3 at US EPA stations near Phoenix. The high PM concentration is consistent in space and time with the dust wall movement based on our analysis of radar data on hydrometeor classification. Enhanced aerosol loadings over metropolitan Phoenix were also observed on 6 July from NASA Terra/Aqua MODIS aerosol optical depth (AOD) retrievals (AOD>0.8). We infer from CALIOP vertical feature masks and HYSPLIT back trajectories that remnants of the haboob were transported to northwest of Phoenix on 6 July at 2-4km above ground level. Ratios of PM2.5 to PM10 from IMPROVE stations also imply low-level transport to the east of Phoenix on 8 July. Finally, we find that this haboob, which had local and regional impacts, is atypical of other dust events in this region. We note from this analysis that extreme events such as this haboob require an integrated air quality observing system to provide a more comprehensive assessment of these events. © 2014 Elsevier Ltd.
• Raman, A., Arellano, A. F., & Brost, J. J. (2014). Revisiting haboobs in the southwestern United States: An observational case study of the 5 July 2011 Phoenix dust storm. Atmospheric Environment, 89(Issue). doi:10.1016/j.atmosenv.2014.02.026
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  Convectively-driven dust storms (or haboobs) are common phenomena in the southwestern United States. However, studies about haboobs in this region are limited. Here, we investigate the state and fate of a massive haboob that hit Phoenix, Arizona on 5 July 2011 using satellite, radar, and ground-based observations. This haboob was a result of strong outflow boundaries (with peak wind gusts of 29ms-1) from storms that were initiated in the southeast of Tucson. In particular, we find three major outflow systems (based on radar data) that were generated by forward propagating storms, ultimately merging near Phoenix. This resulted in peak hourly PM10 and PM2.5 concentrations of 1974μgm-3 and 907μgm-3 at US EPA stations near Phoenix. The high PM concentration is consistent in space and time with the dust wall movement based on our analysis of radar data on hydrometeor classification. Enhanced aerosol loadings over metropolitan Phoenix were also observed on 6 July from NASA Terra/Aqua MODIS aerosol optical depth (AOD) retrievals (AOD>0.8). We infer from CALIOP vertical feature masks and HYSPLIT back trajectories that remnants of the haboob were transported to northwest of Phoenix on 6 July at 2-4km above ground level. Ratios of PM2.5 to PM10 from IMPROVE stations also imply low-level transport to the east of Phoenix on 8 July. Finally, we find that this haboob, which had local and regional impacts, is atypical of other dust events in this region. We note from this analysis that extreme events such as this haboob require an integrated air quality observing system to provide a more comprehensive assessment of these events. © 2014 Elsevier Ltd.
• Rosolem, R., Hoar, T., Arellano, A., Anderson, J. L., Shuttleworth, W. J., Zeng, X., & Franz, T. E. (2014). Translating aboveground cosmic-ray neutron intensity to high-frequency soil moisture profiles at sub-kilometer scale. HYDROLOGY AND EARTH SYSTEM SCIENCES, 18(11), 4363-4379.
• Rosolem, R., Hoar, T., Arellano, A., Anderson, J. L., Shuttleworth, W. J., Zeng, X., & Franz, T. E. (2014). Translating aboveground cosmic-ray neutron intensity to high-frequency soil moisture profiles at sub-kilometer scale. Hydrology and Earth System Sciences, 18(Issue 11). doi:10.5194/hess-18-4363-2014
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  Above-ground cosmic-ray neutron measurements provide an opportunity to infer soil moisture at the sub-kilometer scale. Initial efforts to assimilate those measurements have shown promise. This study expands such analysis by investigating (1) how the information from aboveground cosmic-ray neutrons can constrain the soil moisture at distinct depths simulated by a land surface model, and (2) how changes in data availability (in terms of retrieval frequency) impact the dynamics of simulated soil moisture profiles. We employ ensemble data assimilation techniques in a "nearly-identical twin" experiment applied at semi-arid shrubland, rainfed agricultural field, and mixed forest biomes in the USA. The performance of the Noah land surface model is compared with and without assimilation of observations at hourly intervals, as well as every 2 days. Synthetic observations of aboveground cosmic-ray neutrons better constrain the soil moisture simulated by Noah in root-zone soil layers (0-100cm), despite the limited measurement depth of the sensor (estimated to be 12-20cm). The ability of Noah to reproduce a "true" soil moisture profile is remarkably good, regardless of the frequency of observations at the semi-arid site. However, soil moisture profiles are better constrained when assimilating synthetic cosmic-ray neutron observations hourly rather than every 2 days at the cropland and mixed forest sites. This indicates potential benefits for hydrometeorological modeling when soil moisture measurements are available at a relatively high frequency. Moreover, differences in summertime meteorological forcing between the semi-arid site and the other two sites may indicate a possible controlling factor to soil moisture dynamics in addition to differences in soil and vegetation properties.
• Zeng, X., Shuttleworth, W. J., Rosolem, R., Hoar, T. J., Franz, T. E., Arellano, A. F., & Anderson, J. L. (2014). Assimilation of near-surface cosmic-ray neutrons improves summertime soil moisture profile estimates at three distinct biomes in the USA. Hydrology and Earth System Sciences Discussions, 11(5), 5515-5558. doi:10.5194/hessd-11-5515-2014
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  Abstract. Aboveground cosmic-ray neutron measurements provide an opportunity to infer soil moisture at the sub-kilometer scale. Initial efforts to assimilate those measurements have shown promise. This study expands such analysis by investigating (1) how the information from aboveground cosmic-ray neutrons can constrain the soil moisture at distinct depths simulated by a land surface model, and (2) how changes in data availability (in terms of retrieval frequency) impact the dynamics of simulated soil moisture profiles. We employ ensemble data assimilation techniques in a "nearly-identical twin" experiment applied at semi-arid shrubland, rainfed agricultural field, and mixed forest biomes in the USA The performance of the Noah land surface model is compared without and with assimilation of observations at hourly intervals and every 2 days Synthetic observations of aboveground cosmic-ray neutrons better constrain the soil moisture simulated by Noah in root zone soil layers (0–100 cm) despite the limited measurement depth of the sensor (estimated to be 12–20 cm). The ability of Noah to reproduce a "true" soil moisture profile is remarkably good regardless of the frequency of observations at the semi-arid site. However, soil moisture profiles are better constrained when assimilating synthetic cosmic-ray neutrons observations hourly rather than every 2 days at the cropland and mixed forest sites. This indicates potential benefits for hydrometeorological modeling when soil moisture measurements are available at relatively high frequency. Moreover, differences in summertime meteorological forcing between the semi-arid site and the other two sites may indicate a possible controlling factor to soil moisture dynamics in addition to differences in soil and vegetation properties.
• Lopez, D. H., Rabbani, M. R., Crosbie, E., Raman, A., Arellano, A. F., & Sorooshian, A. (2016). Frequency and Character of Extreme Aerosol Events in the Southwestern United States: A Case Study Analysis in Arizona. Atmosphere, 7(1).
• Silva, S. J., Arellano, A. F., & Worden, H. M. (2013). Toward anthropogenic combustion emission constraints from space-based analysis of urban CO2/CO sensitivity. Geophysical Research Letters, 40(Issue 18). doi:10.1002/grl.50954
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  We explore the value of multispectral CO retrievals from NASA/Terra Measurement of Pollution In The Troposphere (MOPITT v5), along with Atmospheric CO2 Observations from Space (ACOSv2.9) CO2 retrievals from the Japan Aerospace Exploration Agency Greenhouse Gases Observing Satellite (GOSAT), for characterizing emissions from anthropogenic combustion. We use these satellite retrievals to analyze observed CO2/CO enhancement ratios (ΔCO2/ΔCO) over megacities. Since CO is coemitted with CO2 in anthropogenic combustion, the observed ΔCO 2/ΔCO characterizes the general trend in combustion activity. Our analyses show patterns in ΔCO2/ΔCO that correspond well with the developed/developing status of megacities, and ΔCO 2/ΔCO that agree well with available literature and emission inventories to approximately 20%. Comparisons with ΔCO2/ ΔCO derived from Total Carbon Column Observing Network measurements show similar agreement, where some of the differences in observed ΔCO 2/ΔCO are due to representativeness and limited GOSAT data. Our results imply potential constraints in anthropogenic combustion from GOSAT/MOPITT, particularly in augmenting our carbon monitoring systems. © 2013. American Geophysical Union. All Rights Reserved.
• Silva, S. J., Arellano, A. F., & Worden, H. M. (2013). Toward anthropogenic combustion emission constraints from space-based analysis of urban CO₂/CO sensitivity. Geophysical Research Letters, 40(18), 4971-4976.
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  Abstract: We explore the value of multispectral CO retrievals from NASA/Terra Measurement of Pollution In The Troposphere (MOPITT v5), along with Atmospheric CO2 Observations from Space (ACOSv2.9) CO2 retrievals from the Japan Aerospace Exploration Agency Greenhouse Gases Observing Satellite (GOSAT), for characterizing emissions from anthropogenic combustion. We use these satellite retrievals to analyze observed CO2/CO enhancement ratios (ΔCO2/ΔCO) over megacities. Since CO is coemitted with CO2 in anthropogenic combustion, the observed ΔCO 2/ΔCO characterizes the general trend in combustion activity. Our analyses show patterns in ΔCO2/ΔCO that correspond well with the developed/developing status of megacities, and ΔCO 2/ΔCO that agree well with available literature and emission inventories to approximately 20%. Comparisons with ΔCO2/ ΔCO derived from Total Carbon Column Observing Network measurements show similar agreement, where some of the differences in observed ΔCO 2/ΔCO are due to representativeness and limited GOSAT data. Our results imply potential constraints in anthropogenic combustion from GOSAT/MOPITT, particularly in augmenting our carbon monitoring systems. © 2013. American Geophysical Union. All Rights Reserved.
• Worden, H. M., Edwards, D. P., Deeter, M. N., Fu, D., Kulawik, S. S., Worden, J. R., & Arellano, A. (2013). Averaging kernel prediction from atmospheric and surface state parameters based on multiple regression for nadir-viewing satellite measurements of carbon monoxide and ozone. Atmospheric Measurement Techniques, 6(7), 1633-1646.
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  Abstract: A current obstacle to the observation system simulation experiments (OSSEs) used to quantify the potential performance of future atmospheric composition remote sensing systems is a computationally efficient method to define the scene-dependent vertical sensitivity of measurements as expressed by the retrieval averaging kernels (AKs). We present a method for the efficient prediction of AKs for multispectral retrievals of carbon monoxide (CO) and ozone (O3) based on actual retrievals from MOPITT (Measurements Of Pollution In The Troposphere) on the Earth Observing System (EOS)-Terra satellite and TES (Tropospheric Emission Spectrometer) and OMI (Ozone Monitoring Instrument) on EOS-Aura, respectively. This employs a multiple regression approach for deriving scene-dependent AKs using predictors based on state parameters such as the thermal contrast between the surface and lower atmospheric layers, trace gas volume mixing ratios (VMRs), solar zenith angle, water vapor amount, etc. We first compute the singular value decomposition (SVD) for individual cloud-free AKs and retain the first three ranked singular vectors in order to fit the most significant orthogonal components of the AK in the subsequent multiple regression on a training set of retrieval cases. The resulting fit coefficients are applied to the predictors from a different test set of test retrievals cased to reconstruct predicted AKs, which can then be evaluated against the true retrieval AKs from the test set. By comparing the VMR profile adjustment resulting from the use of the predicted vs. true AKs, we quantify the CO and O3 VMR profile errors associated with the use of the predicted AKs compared to the true AKs that might be obtained from a computationally expensive full retrieval calculation as part of an OSSE. Similarly, we estimate the errors in CO and O3 VMRs from using a single regional average AK to represent all retrievals, which has been a common approximation in chemical OSSEs performed to date. For both CO and O3 in the lower troposphere, we find a significant reduction in error when using the predicted AKs as compared to a single average AK. This study examined data from the continental United States (CONUS) for 2006, but the approach could be applied to other regions and times. © 2013 Author(s).
• Worden, H. M., Edwards, D. P., Deeter, M. N., Fu, D., Kulawik, S. S., Worden, J. R., & Arellano, A. (2013). Averaging kernel prediction from atmospheric and surface state parameters based on multiple regression for nadir-viewing satellite measurements of carbon monoxide and ozone. Atmospheric Measurement Techniques, 6(Issue 7). doi:10.5194/amt-6-1633-2013
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  A current obstacle to the observation system simulation experiments (OSSEs) used to quantify the potential performance of future atmospheric composition remote sensing systems is a computationally efficient method to define the scene-dependent vertical sensitivity of measurements as expressed by the retrieval averaging kernels (AKs). We present a method for the efficient prediction of AKs for multispectral retrievals of carbon monoxide (CO) and ozone (O3) based on actual retrievals from MOPITT (Measurements Of Pollution In The Troposphere) on the Earth Observing System (EOS)-Terra satellite and TES (Tropospheric Emission Spectrometer) and OMI (Ozone Monitoring Instrument) on EOS-Aura, respectively. This employs a multiple regression approach for deriving scene-dependent AKs using predictors based on state parameters such as the thermal contrast between the surface and lower atmospheric layers, trace gas volume mixing ratios (VMRs), solar zenith angle, water vapor amount, etc. We first compute the singular value decomposition (SVD) for individual cloud-free AKs and retain the first three ranked singular vectors in order to fit the most significant orthogonal components of the AK in the subsequent multiple regression on a training set of retrieval cases. The resulting fit coefficients are applied to the predictors from a different test set of test retrievals cased to reconstruct predicted AKs, which can then be evaluated against the true retrieval AKs from the test set. By comparing the VMR profile adjustment resulting from the use of the predicted vs. true AKs, we quantify the CO and O3 VMR profile errors associated with the use of the predicted AKs compared to the true AKs that might be obtained from a computationally expensive full retrieval calculation as part of an OSSE. Similarly, we estimate the errors in CO and O3 VMRs from using a single regional average AK to represent all retrievals, which has been a common approximation in chemical OSSEs performed to date. For both CO and O3 in the lower troposphere, we find a significant reduction in error when using the predicted AKs as compared to a single average AK. This study examined data from the continental United States (CONUS) for 2006, but the approach could be applied to other regions and times. © 2013 Author(s).
• Youn, J. S., Wang, Z., Wonaschütz, A., Arellano, A., Betterton, E. A., & Sorooshian, A. (2013). Evidence of aqueous secondary organic aerosol formation from biogenic emissions in the North American Sonoran Desert. Geophysical Research Letters, 40(Issue 13). doi:10.1002/grl.50644
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  This study examines the role of aqueous secondary organic aerosol formation in the North American Sonoran Desert as a result of intense solar radiation, enhanced moisture, and biogenic volatile organic compounds (BVOCs). The ratio of water-soluble organic carbon (WSOC) to organic carbon (OC) nearly doubles during the monsoon season relative to other seasons of the year. When normalized by mixing height, the WSOC enhancement during monsoon months relative to preceding dry months (May-June) exceeds that of sulfate by nearly a factor of 10. WSOC:OC and WSOC are most strongly correlated with moisture parameters, temperature, and concentrations of O3 and BVOCs. No positive relationship was identified between WSOC or WSOC:OC and anthropogenic tracers such as CO over a full year. This study points at the need for further work to understand the effect of BVOCs and moisture in altering aerosol properties in understudied desert regions. Key Points Evidence of aqueous SOA formation in the Sonoran Desert Biogenic emissions assist in WSOC formation in this desert region WSOC production greatly exceeds that of sulfate during the monsoon season ©2013. American Geophysical Union. All Rights Reserved.
• Youn, J., Wang, Z., Wonaschuetz, A., Arellano, A., Betterton, E. A., & Sorooshian, A. (2013). Evidence of aqueous secondary organic aerosol formation from biogenic emissions in the North American Sonoran Desert. GEOPHYSICAL RESEARCH LETTERS, 40(13), 3468-3472.
• Hyer, E. J., Wang, J., & Arellano, A. F. (2012). Biomass Burning - Observations, Modeling, and Data Assimilation. Bulletin of the American Meteorological Society. doi:10.1175/BAMS-D-11-00064.1
• Friedli, H. R., Arellano Jr., A. F., Geng, F., Cai, C., & Pan, L. (2011). Measurements of atmospheric mercury in Shanghai during September 2009. Atmospheric Chemistry and Physics, 11(8), 3781-3788.
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  Abstract: We report on total gaseous mercury (TGM) measurements made in Pudong, Shanghai in August/September 2009. The average TGM was 2.7 ± 1.7 ng mg-3. This represents about 90% of the total atmospheric mercury. This is an underestimate for an annual-mean concentration because the meteorology in September favored predominantly easterly oceanic air, replaced in other seasons by airflow from industrial areas. The observed TGM follows a pattern seen in other cities around the world: a background elevated over mean hemispheric background (1.5 ng m-3), and pollution plumes of different magnitude and duration, interspersed with very sharp spikes of high concentration (60 ng mg-3). The September 2009 Shanghai measurements are lower than those reported for most other Chinese cities and Mexico City, and similar to concentrations found in some Asian and in North American cities. Such comparisons are tenuous because of differences in season and year of the respective measurements. Our results should not be used for regulatory purposes. We find that the observed TGM are most likely coming from coal fired power plants, smelters and industrial sources, based on its high correlation with NOx, SO2, CO and wind directions. © 2011 Author(s).
• Friedli, H. R., Arellano, A. F., Geng, F., Cai, C., & Pan, L. (2011). Measurements of atmospheric mercury in Shanghai during September 2009. Atmospheric Chemistry and Physics, 11(Issue 8). doi:10.5194/acp-11-3781-2011
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  We report on total gaseous mercury (TGM) measurements made in Pudong, Shanghai in August/September 2009. The average TGM was 2.7 ± 1.7 ng mg-3. This represents about 90% of the total atmospheric mercury. This is an underestimate for an annual-mean concentration because the meteorology in September favored predominantly easterly oceanic air, replaced in other seasons by airflow from industrial areas. The observed TGM follows a pattern seen in other cities around the world: a background elevated over mean hemispheric background (1.5 ng m-3), and pollution plumes of different magnitude and duration, interspersed with very sharp spikes of high concentration (60 ng mg-3). The September 2009 Shanghai measurements are lower than those reported for most other Chinese cities and Mexico City, and similar to concentrations found in some Asian and in North American cities. Such comparisons are tenuous because of differences in season and year of the respective measurements. Our results should not be used for regulatory purposes. We find that the observed TGM are most likely coming from coal fired power plants, smelters and industrial sources, based on its high correlation with NOx, SO2, CO and wind directions. © 2011 Author(s).
• Arellano Jr., A. F., Hess, P. G., Edwards, D. P., & Baumgardner, D. (2010). Constraints on black carbon aerosol distribution from Measurement of Pollution in the Troposphere (MOPITT) CO. Geophysical Research Letters, 37(17).
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  Abstract: We present an approach to constrain simulated atmospheric black carbon (BC) using carbon monoxide (CO) observations. The approach uses: (1) the Community Atmosphere Model with Chemistry to simulate the evolution of BC and CO within an ensemble of model simulations; (2) satellite CO retrievals from the MOPITT/Terra instrument to assimilate observed CO into these simulations; (3) the derived sensitivity of BC to CO within these simulations to correct the simulated BC distributions. We demonstrate the performance of this approach through model experiments with and without the BC corrections during the period coinciding with the Intercontinental Chemical Transport Experiment (INTEX-B). Our results show significant improvements (∼50%) in median BC profiles using constraints from MOPITT, based on comparisons with INTEX-B measurements. We find that assimilating MOPITT CO provides considerable impact on simulated BC concentrations, especially over source regions. This approach offers an opportunity to augment our current ability to predict BC distributions. © 2010 by the American Geophysical Union.
• Arellano, A. F., Hess, P. G., Edwards, D. P., & Baumgardner, D. (2010). Constraints on black carbon aerosol distribution from Measurement of Pollution in the Troposphere (MOPITT) CO. Geophysical Research Letters, 37(Issue 17). doi:10.1029/2010gl044416
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  We present an approach to constrain simulated atmospheric black carbon (BC) using carbon monoxide (CO) observations. The approach uses: (1) the Community Atmosphere Model with Chemistry to simulate the evolution of BC and CO within an ensemble of model simulations; (2) satellite CO retrievals from the MOPITT/Terra instrument to assimilate observed CO into these simulations; (3) the derived sensitivity of BC to CO within these simulations to correct the simulated BC distributions. We demonstrate the performance of this approach through model experiments with and without the BC corrections during the period coinciding with the Intercontinental Chemical Transport Experiment (INTEX-B). Our results show significant improvements (∼50%) in median BC profiles using constraints from MOPITT, based on comparisons with INTEX-B measurements. We find that assimilating MOPITT CO provides considerable impact on simulated BC concentrations, especially over source regions. This approach offers an opportunity to augment our current ability to predict BC distributions. © 2010 by the American Geophysical Union.
• Pfister, G., Emmons, L. K., Edwards, D. P., Arellano, A., Sachse, G., & Campos, T. (2010). Variability of springtime transpacific pollution transport during 2000-2006: The INTEX-B mission in the context of previous years. Atmospheric Chemistry and Physics, 10(3), 1345-1359.
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  Abstract: We analyze the transport of pollution across the Pacific during the NASA INTEX-B (Intercontinental Chemical Transport Experiment Part B) campaign in spring 2006 and examine how this year compares to the time period for 2000 through 2006. In addition to aircraft measurements of carbon monoxide (CO) collected during INTEX-B, we include in this study multi-year satellite retrievals of CO from the Measurements of Pollution in the Troposphere (MOPITT) instrument and simulations from the chemistry transport model MOZART-4. Model tracers are used to examine the contributions of different source regions and source types to pollution levels over the Pacific. Additional modeling studies are performed to separate the impacts of inter-annual variability in meteorology and dynamics from changes in source strength. Interannual variability in the tropospheric CO burden over the Pacific and the US as estimated from the MOPITT data range up to 7% and a somewhat smaller estimate (5%) is derived from the model. When keeping the emissions in the model constant between years, the year-to-year changes are reduced (2%), but show that in addition to changes in emissions, variable meteorological conditions also impact transpacific pollution transport. We estimate that about 1/3 of the variability in the tropospheric CO loading over the contiguous US is explained by changes in emissions and about 2/3 by changes in meteorology and transport. Biomass burning sources are found to be a larger driver for inter-annual variability in the CO loading compared to fossil and biofuel sources or photochemical CO production even though their absolute contributions are smaller. Source contribution analysis shows that the aircraft sampling during INTEX-B was fairly representative of the larger scale region, but with a slight bias towards higher influence from Asian contributions.
• Pfister, G., Emmons, L. K., Edwards, D. P., Arellano, A., Sachse, G., & Campos, T. (2010). Variability of springtime transpacific pollution transport during 2000-2006: The INTEX-B mission in the context of previous years. Atmospheric Chemistry and Physics, 10(Issue 3). doi:10.5194/acp-10-1345-2010
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  We analyze the transport of pollution across the Pacific during the NASA INTEX-B (Intercontinental Chemical Transport Experiment Part B) campaign in spring 2006 and examine how this year compares to the time period for 2000 through 2006. In addition to aircraft measurements of carbon monoxide (CO) collected during INTEX-B, we include in this study multi-year satellite retrievals of CO from the Measurements of Pollution in the Troposphere (MOPITT) instrument and simulations from the chemistry transport model MOZART-4. Model tracers are used to examine the contributions of different source regions and source types to pollution levels over the Pacific. Additional modeling studies are performed to separate the impacts of inter-annual variability in meteorology and dynamics from changes in source strength. Interannual variability in the tropospheric CO burden over the Pacific and the US as estimated from the MOPITT data range up to 7% and a somewhat smaller estimate (5%) is derived from the model. When keeping the emissions in the model constant between years, the year-to-year changes are reduced (2%), but show that in addition to changes in emissions, variable meteorological conditions also impact transpacific pollution transport. We estimate that about 1/3 of the variability in the tropospheric CO loading over the contiguous US is explained by changes in emissions and about 2/3 by changes in meteorology and transport. Biomass burning sources are found to be a larger driver for inter-annual variability in the CO loading compared to fossil and biofuel sources or photochemical CO production even though their absolute contributions are smaller. Source contribution analysis shows that the aircraft sampling during INTEX-B was fairly representative of the larger scale region, but with a slight bias towards higher influence from Asian contributions.
• Prabhakar, G., Sorooshian, A., Toffol, E., Arellano, A. F., & Betterton, E. A. (2014). Spatiotemporal distribution of airborne particulate metals and metalloids in a populated arid region. ATMOSPHERIC ENVIRONMENT, 92, 339-347.
• Anderson, J., Hoar, T., Raeder, K., Liu, H., Collins, N., Torn, R., & Avellano, A. (2009). THE DATA ASSIMILATION RESEARCH TESTBED A Community Facility. BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, 90(9), 1283-1296.
• Edwards, D. P., Arellano Jr., A. F., & N., M. (2009). A satellite observation system simulation experiment for carbon monoxide in the lowermost troposphere. Journal of Geophysical Research D: Atmospheres, 114(14).
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  Abstract: We demonstrate the feasibility of using observing system simulation experiment (OSSE) studies to help define quantitative trace gas measurement requirements for satellite missions and to evaluate the expected performance of proposed observing strategies. The 2007 U.S. National Research Council Decadal Survey calls for a geostationary (GEO) satellite mission for atmospheric composition and air quality applications (Geostationary Coastal and Air Pollution Events Mission (GEO-CAPE)). The requirement includes a multispectral (near-infrared and thermal infrared) measurement of carbon monoxide (CO) at high spatiotemporal resolution with information on lowermost troposphere concentration. We present an OSSE to assess the improvement in surface CO characterization that would result from the addition of a GEO-CAPE CO measurement to current low Earth orbit (LEO) thermal infrared-only measurements. We construct instrument simulators for these two measurement scenarios and study the case of July 2004 when wildfires in Alaska and Canada led to significant CO pollution over the contiguous United States. Compared to a control experiment, an ensemble-based data assimilation of simulated satellite observations in a global model leads to improvements in both the surface CO distributions and the time evolution of CO profiles at locations affected by wildfire plumes and by urban emissions. In all cases, an experiment with the GEO-CAPE CO measurement scenario (overall model skill of 0.84) performed considerably better than the experiment with the current LEO/thermal infrared measurement (skill of 0.58) and the control (skill of 0.07). This demonstrates the advantages of increased sampling from GEO and enhanced measurement sensitivity to the lowermost troposphere with a multispectral retrieval. Copyright 2009 by the American Geophysical Union.
• Edwards, D. P., Arellano, A. F., & Deeter P, M. N. (2009). A satellite observation system simulation experiment for carbon monoxide in the lowermost troposphere. Journal of Geophysical Research Atmospheres, 114(Issue 14). doi:10.1029/2008jd011375
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  We demonstrate the feasibility of using observing system simulation experiment (OSSE) studies to help define quantitative trace gas measurement requirements for satellite missions and to evaluate the expected performance of proposed observing strategies. The 2007 U.S. National Research Council Decadal Survey calls for a geostationary (GEO) satellite mission for atmospheric composition and air quality applications (Geostationary Coastal and Air Pollution Events Mission (GEO-CAPE)). The requirement includes a multispectral (near-infrared and thermal infrared) measurement of carbon monoxide (CO) at high spatiotemporal resolution with information on lowermost troposphere concentration. We present an OSSE to assess the improvement in surface CO characterization that would result from the addition of a GEO-CAPE CO measurement to current low Earth orbit (LEO) thermal infrared-only measurements. We construct instrument simulators for these two measurement scenarios and study the case of July 2004 when wildfires in Alaska and Canada led to significant CO pollution over the contiguous United States. Compared to a control experiment, an ensemble-based data assimilation of simulated satellite observations in a global model leads to improvements in both the surface CO distributions and the time evolution of CO profiles at locations affected by wildfire plumes and by urban emissions. In all cases, an experiment with the GEO-CAPE CO measurement scenario (overall model skill of 0.84) performed considerably better than the experiment with the current LEO/thermal infrared measurement (skill of 0.58) and the control (skill of 0.07). This demonstrates the advantages of increased sampling from GEO and enhanced measurement sensitivity to the lowermost troposphere with a multispectral retrieval. Copyright 2009 by the American Geophysical Union.
• Friedli, H. R., Arellano Jr., A. F., Cinnirella, S., & Pirrone, N. (2009). Mercury emissions from global biomass burning: Spatialand temporal distribution. Mercury Fate and Transport in the Global Atmosphere: Emissions, Measurements and Models, 193-220.
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  Abstract: This chapter represents a new addition to the UNEP global mercury budget: the mercury emissions from biomass burning, here defined as emissions from wildfires and prescribed burns, and excluding contributions from bio-fuel consumption and charcoal production and use. The results cover the 1997-2006 timeframe. The average annual global mercury emission estimate from biomass burning for 1997-2006 is 675 ± 240 Mg yr-1. This accounts for 8% of all current anthropogenic and natural emissions. The largest Hg emissions are from tropical and boreal Asia, followed by Africa and South America. They do not coincide with the largest carbon biomass burning emissions, which originate from Africa. Our methodology for budget estimation is based on a satellite-constrained bottom-up global carbon fire emission database (GFED version 2), which divides the globe into regions with similar ecosystems and burn behaviour. To estimate mercury emissions, the carbon model output is paired with regional emission factors for Hg, EF(Hg). There are large uncertainties in the budget estimation associated with burned area, fuel mass, and combustion completeness. The discrepancy between the model and traditional ground based assessments (e.g. FRA, 2000) is unacceptably large at this time. Of great urgency is the development and validation of a model for mercury cycling in forests, accounting for the biogeochemistry for each region. This would provide an understanding of the source/sink relationship and thus mercury accumulation or loss in ecosystems. Limiting the burning of tropical and boreal forests would have two beneficial effects: reducing the source of mercury releases to the atmosphere from burning, and maintaining a sink for atmospheric mercury. Restricting the global release mercury would reduce the vegetation/soil pools, and the potential Hg release in case of fire. © 2009 Springer-Verlag New York.
• Friedli, H. R., Arellano, A. F., Cinnirella, S., & Pirrone, N. (2009). Initial estimates of mercury emissions to the atmosphere from global biomass burning. Environmental Science and Technology, 43(10), 3507-3513.
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  PMID: 19544847;Abstract: The average global annual mercury emission estimate from biomass burning (BMB) for 1997-2006 is 675 ± 240 Mg/year. This is equivalent to 8% of all currently known anthropogenic and natural mercury emissions. By season, the largest global emissions occur in August and September, the lowest during northern winters. The interannual variability is large and region-specific, and responds to drought conditions. During this particular time period, the largest mercury emissions are from tropical and boreal Asia, followed by Africa and South America. They do not coincide with the largest carbon biomass burning emissions, which originate from Africa. Frequently burning grasslands in Africa and Australia, and agricultural waste burning globally, contribute relatively little to the mercury budget. The released mercury from BMB is eventually deposited locally and globally and contributes to the formation of toxic bioaccumulating methyl mercury. Furthermore, increasing temperature in boreal regions, where the largest soil mercury pools reside, is expected to exacerbate mercury emission because of more frequent, larger, and more intense fires. © 2009 American Chemical Society.
• Friedli, H. R., Arellano, A. F., Cinnirella, S., & Pirrone, N. (2009). Initial estimates of mercury emissions to the atmosphere from global biomass burning. Environmental Science and Technology, 43(Issue 10). doi:10.1021/es802703g
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  The average global annual mercury emission estimate from biomass burning (BMB) for 1997-2006 is 675 ± 240 Mg/year. This is equivalent to 8% of all currently known anthropogenic and natural mercury emissions. By season, the largest global emissions occur in August and September, the lowest during northern winters. The interannual variability is large and region-specific, and responds to drought conditions. During this particular time period, the largest mercury emissions are from tropical and boreal Asia, followed by Africa and South America. They do not coincide with the largest carbon biomass burning emissions, which originate from Africa. Frequently burning grasslands in Africa and Australia, and agricultural waste burning globally, contribute relatively little to the mercury budget. The released mercury from BMB is eventually deposited locally and globally and contributes to the formation of toxic bioaccumulating methyl mercury. Furthermore, increasing temperature in boreal regions, where the largest soil mercury pools reside, is expected to exacerbate mercury emission because of more frequent, larger, and more intense fires. © 2009 American Chemical Society.
• Sachse, G. W., Pfister, G., Emmons, L. K., Edwards, D., Campos, T., & Arellano, A. F. (2009). Transpacific pollution transport during INTEX-B: spring 2006 in context to previous years. Atmospheric Chemistry and Physics, 9(4), 17817-17849.
• Malmberg, A., Arellano, A., Edwards, D. P., Flyer, N., Nychka, D., & Wikle, C. (2008). Interpolating fields of carbon monoxide data using a hybrid statistical-physical model. Annals of Applied Statistics, 2(4), 1231-1248.
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  Abstract: Atmospheric Carbon Monoxide (CO) provides a window on the chemistry of the atmosphere since it is one of few chemical constituents that can be remotely sensed, and it can be used to determine budgets of other greenhouse gases such as ozone and OH radicals. Remote sensing platforms in geostationary Earth orbit will soon provide regional observations of CO at several vertical layers with high spatial and temporal resolution. However, cloudy locations cannot be observed and estimates of the complete CO concentration fields have to be estimated based on the cloud-free observations. The current state-of-the-art solution of this interpolation problem is to combine cloud-free observations with prior information, computed by a deterministic physical model, which might introduce uncertainties that do not derive from data. While sharing features with the physical model, this paper suggests a Bayesian hierarchical model to estimate the complete CO concentration fields. The paper also provides a direct comparison to state-of-the-art methods. To our knowledge, such a model and comparison have not been considered before. © Institute of Mathematical Statistics.
• Malmberg, A., Arellano, A., Edwards, D. P., Flyer, N., Nychka, D., & Wikle, C. (2008). Interpolating fields of carbon monoxide data using a hybrid statistical-physical model. Annals of Applied Statistics, 2(Issue 4). doi:10.1214/08-aoas168
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  Atmospheric Carbon Monoxide (CO) provides a window on the chemistry of the atmosphere since it is one of few chemical constituents that can be remotely sensed, and it can be used to determine budgets of other greenhouse gases such as ozone and OH radicals. Remote sensing platforms in geostationary Earth orbit will soon provide regional observations of CO at several vertical layers with high spatial and temporal resolution. However, cloudy locations cannot be observed and estimates of the complete CO concentration fields have to be estimated based on the cloud-free observations. The current state-of-the-art solution of this interpolation problem is to combine cloud-free observations with prior information, computed by a deterministic physical model, which might introduce uncertainties that do not derive from data. While sharing features with the physical model, this paper suggests a Bayesian hierarchical model to estimate the complete CO concentration fields. The paper also provides a direct comparison to state-of-the-art methods. To our knowledge, such a model and comparison have not been considered before. © Institute of Mathematical Statistics.
• Arellano Jr., A. F., Raeder, K., Anderson, J. L., Hess, P. G., Emmons, L. K., Edwards, D. P., Pflster, G. G., Campos, T. L., & Sachse, G. W. (2007). Evaluating model performance of an ensemble-based chemical data assimilation system during INTEX-B field mission. Atmospheric Chemistry and Physics, 7(21), 5695-5710.
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  Abstract: We present a global chemical data assimilation system using a global atmosphere model, the Community Atmosphere Model (CAM3) with simplified chemistry and the Data Assimilation Research Testbed (DART) assimilation package. DART is a community software facility for assimilation studies using the ensemble Kalman filter approach. Here, we apply the assimilation system to constrain global tropospheric carbon monoxide (CO) by assimilating meteorological observations of temperature and horizontal wind velocity and satellite CO retrievals from the Measurement of Pollution in the Troposphere (MOPITT) satellite instrument. We verify the system performance using independent CO observations taken on board the NSF/NCAR C-130 and NASA DC-8 aircrafts during the April 2006 part of the Intercontinental Chemical Transport Experiment (INTEX-B). Our evaluations show that MOPITT data assimilation provides significant improvements in terms of capturing the observed CO variability relative to no MOPITT assimilation (i.e. the correlation improves from 0.62 to 0.71, significant at 99% confidence). The assimilation provides evidence of median CO loading of about 150 ppbv at 700 hPa over the NE Pacific during April 2006. This is marginally higher than the modeled CO with no MOPITT assimilation (∼ 140 ppbv). Our ensemble-based estimates of model uncertainty also show model overprediction over the source region (i.e. China) and underprediction over the NE Pacific, suggesting model errors that cannot be readily explained by emissions alone. These results have important implications for improving regional chemical forecasts and for inverse modeling of CO sources and further demonstrate the utility of the assimilation system in comparing non-coincident measurements, e.g. comparing satellite retrievals of CO with in-situ aircraft measurements.
• Arellano, A. F., Raeder, K., Anderson, J. L., Hess, P. G., Emmons, L. K., Edwards, D. P., Pflster, G. G., Campos, T. L., & Sachse, G. W. (2007). Evaluating model performance of an ensemble-based chemical data assimilation system during INTEX-B field mission. Atmospheric Chemistry and Physics, 7(Issue 21). doi:10.5194/acp-7-5695-2007
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  We present a global chemical data assimilation system using a global atmosphere model, the Community Atmosphere Model (CAM3) with simplified chemistry and the Data Assimilation Research Testbed (DART) assimilation package. DART is a community software facility for assimilation studies using the ensemble Kalman filter approach. Here, we apply the assimilation system to constrain global tropospheric carbon monoxide (CO) by assimilating meteorological observations of temperature and horizontal wind velocity and satellite CO retrievals from the Measurement of Pollution in the Troposphere (MOPITT) satellite instrument. We verify the system performance using independent CO observations taken on board the NSF/NCAR C-130 and NASA DC-8 aircrafts during the April 2006 part of the Intercontinental Chemical Transport Experiment (INTEX-B). Our evaluations show that MOPITT data assimilation provides significant improvements in terms of capturing the observed CO variability relative to no MOPITT assimilation (i.e. the correlation improves from 0.62 to 0.71, significant at 99% confidence). The assimilation provides evidence of median CO loading of about 150 ppbv at 700 hPa over the NE Pacific during April 2006. This is marginally higher than the modeled CO with no MOPITT assimilation (∼ 140 ppbv). Our ensemble-based estimates of model uncertainty also show model overprediction over the source region (i.e. China) and underprediction over the NE Pacific, suggesting model errors that cannot be readily explained by emissions alone. These results have important implications for improving regional chemical forecasts and for inverse modeling of CO sources and further demonstrate the utility of the assimilation system in comparing non-coincident measurements, e.g. comparing satellite retrievals of CO with in-situ aircraft measurements.
• Bian, H., Chin, M., Kawa, S. R., Duncan, B., Arellano, A., & Kasibhatla, P. (2007). Sensitivity of global CO simulations to uncertainties in biomass burning sources. Journal of Geophysical Research Atmospheres, 112(Issue 23). doi:10.1029/2006jd008376
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  One of the largest uncertainties for the modeling of tropospheric carbon monoxide (CO) concentration is the timing, location, and magnitude of biomass burning emissions. We investigate the sensitivity of simulated CO in the Unified Chemistry Transport Model (UCTM) to several biomass burning emissions, including four bottom-up and two top-down inventories. We compare the sensitivity experiments with observations from MOPITT, surface and airborne NOAA Global Monitoring Division network data, and the TRACE-P field campaign. The variation of the global annual emissions of these six biomass burning inventories is within 30%; however, their regional variations are often much higher (factor of 2-5). These uncertainties translate to about 6% variation in the global simulated CO but more than a 100% variation in some regions. The annual mean CO variation is greater in the Southern Hemisphere (>12%) than in the Northern Hemisphere (
• Bian, H., Chin, M., Kawa, S. R., Duncan, B., Arellano, A., & Kasibhatla, P. (2007). Sensitivity of global CO simulations to uncertainties in biomass burning sources. Journal of Geophysical Research D: Atmospheres, 112(23).
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  Abstract: One of the largest uncertainties for the modeling of tropospheric carbon monoxide (CO) concentration is the timing, location, and magnitude of biomass burning emissions. We investigate the sensitivity of simulated CO in the Unified Chemistry Transport Model (UCTM) to several biomass burning emissions, including four bottom-up and two top-down inventories. We compare the sensitivity experiments with observations from MOPITT, surface and airborne NOAA Global Monitoring Division network data, and the TRACE-P field campaign. The variation of the global annual emissions of these six biomass burning inventories is within 30%; however, their regional variations are often much higher (factor of 2-5). These uncertainties translate to about 6% variation in the global simulated CO but more than a 100% variation in some regions. The annual mean CO variation is greater in the Southern Hemisphere (>12%) than in the Northern Hemisphere (
• Arellano Jr., A. F., & Hess, P. G. (2006). Sensitivity of top-down estimates of CO sources to GCTM transport. Geophysical Research Letters, 33(21).
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  Abstract: Estimates of CO sources derived from inversions using satellite observations still exhibit discrepancies. Here, we conduct controlled inverse analyses to elucidate the influence of model transport on the robustness of regional CO source estimates. We utilized Model of Ozone and Related chemical Tracers global chemical transport models (GCTM) driven by National Centers for Environmental Prediction and European Centre for Medium-Range Weather Forecast reanalyses, and GEOS-Chem GCTM driven by Global Modeling and Assimilation Office assimilated meteorology to generate response functions for prescribed regional CO sources. We find that inter-model differences in CO due to differences in transport are within 10-30% of inter-model mean CO concentration. However, these differences can translate to regionally significant spread in source estimates. While we find that CO source estimates for East Asia and North Africa are reasonably robust, we find inconsistencies and inter-model spread of greater than 40% in our source estimates for Indonesia, South America, Europe and Russia. This indicates the need for rigorous assessment on uncertainties in top-down source estimates through model inter-comparisons and ensemble approaches. Copyright 2006 by the American Geophysical Union.
• Arellano Jr., A. F., Kasibhatla, P. S., Giglio, L., R., G., Randerson, J. T., & Collatz, G. J. (2006). Time-dependent inversion estimates of global biomass-burning CO emissions using Measurement of Pollution in the Troposphere (MOPITT) measurements. Journal of Geophysical Research D: Atmospheres, 111(9).
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  Abstract: We present an inverse-modeling analysis of CO emissions using column CO retrievals from the Measurement of Pollution in the Troposphere (MOPITT) instrument and a global chemical transport model (GEOS-CHEM). We first focus on the information content of MOPITT CO column retrievals in terms of constraining CO emissions associated with biomass burning and fossil fuel/biofuel use. Our analysis shows that seasonal variation of biomass-burning CO emissions in Africa, South America, and Southeast Asia can be characterized using monthly mean MOPITT CO columns. For the fossil fuel/biofuel source category the derived monthly mean emission estimates are noisy even when the error statistics are accurately known, precluding a characterization of seasonal variations of regional CO emissions for this source category. The derived estimate of CO emissions from biomass burning in southern Africa during the June-July 2000 period is significantly higher than the prior estimate (prior, 34 Tg; posterior, 13 Tg). We also estimate that emissions are higher relative to the prior estimate in northern Africa during December 2000 to January 2001 and lower relative to the prior estimate in Central America and Oceania/Indonesia during April-May and September-October 2000, respectively. While these adjustments provide better agreement of the model with MOPITT CO column fields and with independent measurements of surface CO from National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory at background sites in the Northern Hemisphere, some systematic differences between modeled and measured CO fields persist, including model overestimation of background surface CO in the Southern Hemisphere. Characterizing and accounting for underlying biases in the measurement model system are needed to improve the robustness of the top-down estimate. Copyright 2006 by the American Geophysical Union.
• Arellano, A. F., & Hess, P. G. (2006). Sensitivity of top-down estimates of CO sources to GCTM transport. Geophysical Research Letters, 33(Issue 21). doi:10.1029/2006gl027371
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  Estimates of CO sources derived from inversions using satellite observations still exhibit discrepancies. Here, we conduct controlled inverse analyses to elucidate the influence of model transport on the robustness of regional CO source estimates. We utilized Model of Ozone and Related chemical Tracers global chemical transport models (GCTM) driven by National Centers for Environmental Prediction and European Centre for Medium-Range Weather Forecast reanalyses, and GEOS-Chem GCTM driven by Global Modeling and Assimilation Office assimilated meteorology to generate response functions for prescribed regional CO sources. We find that inter-model differences in CO due to differences in transport are within 10-30% of inter-model mean CO concentration. However, these differences can translate to regionally significant spread in source estimates. While we find that CO source estimates for East Asia and North Africa are reasonably robust, we find inconsistencies and inter-model spread of greater than 40% in our source estimates for Indonesia, South America, Europe and Russia. This indicates the need for rigorous assessment on uncertainties in top-down source estimates through model inter-comparisons and ensemble approaches. Copyright 2006 by the American Geophysical Union.
• Arellano, A. F., Kasibhatla, P. S., Giglio, L., van der Werf, G. R., Randerson, J. T., & Collatz, G. J. (2006). Time-dependent inversion estimates of global biomass-burning CO emissions using Measurement of Pollution in the Troposphere (MOPITT) measurements. Journal of Geophysical Research Atmospheres, 111(Issue 9). doi:10.1029/2005jd006613
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  We present an inverse-modeling analysis of CO emissions using column CO retrievals from the Measurement of Pollution in the Troposphere (MOPITT) instrument and a global chemical transport model (GEOS-CHEM). We first focus on the information content of MOPITT CO column retrievals in terms of constraining CO emissions associated with biomass burning and fossil fuel/biofuel use. Our analysis shows that seasonal variation of biomass-burning CO emissions in Africa, South America, and Southeast Asia can be characterized using monthly mean MOPITT CO columns. For the fossil fuel/biofuel source category the derived monthly mean emission estimates are noisy even when the error statistics are accurately known, precluding a characterization of seasonal variations of regional CO emissions for this source category. The derived estimate of CO emissions from biomass burning in southern Africa during the June-July 2000 period is significantly higher than the prior estimate (prior, 34 Tg; posterior, 13 Tg). We also estimate that emissions are higher relative to the prior estimate in northern Africa during December 2000 to January 2001 and lower relative to the prior estimate in Central America and Oceania/Indonesia during April-May and September-October 2000, respectively. While these adjustments provide better agreement of the model with MOPITT CO column fields and with independent measurements of surface CO from National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory at background sites in the Northern Hemisphere, some systematic differences between modeled and measured CO fields persist, including model overestimation of background surface CO in the Southern Hemisphere. Characterizing and accounting for underlying biases in the measurement model system are needed to improve the robustness of the top-down estimate. Copyright 2006 by the American Geophysical Union.
• Friedli, H. R., Arellano, A. F., Cinnirella, S., Pirrone, N., Pirrone, N., & Mason, R. (2006). Mercury Emissions from Global Biomass Burning: Spatial and Temporal Distribution. MERCURY FATE AND TRANSPORT IN THE GLOBAL ATMOSPHERE, 193-220.
• Van Der Werf, G. R., Randerson, J. T., Giglio, L., Collatz, G. J., Kasibhatla, P. S., & Arellano, A. F. (2006). Interannual variability in global biomass burning emissions from 1997 to 2004. Atmospheric Chemistry and Physics, 6(Issue 11). doi:10.5194/acp-6-3423-2006
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  Biomass burning represents an important source of atmospheric aerosols and greenhouse gases, yet little is known about its interannual variability or the underlying mechanisms regulating this variability at continental to global scales. Here we investigated fire emissions during the 8 year period from 1997 to 2004 using satellite data and the CASA biogeochemical model. Burned area from 2001-2004 was derived using newly available active fire and 500 m. burned area datasets from MODIS following the approach described by Giglio et al. (2006). ATSR and VIRS satellite data were used to extend the burned area time series back in time through 1997. In our analysis we estimated fuel loads, including organic soil layer and peatland fuels, and the net flux from terrestrial ecosystems as the balance between net primary production (NPP), heterotrophic respiration (Rh), and biomass burning, using time varying inputs of precipitation (PPT), temperature, solar radiation, and satellite-derived fractional absorbed photosynthetically active radiation (fAPAR). For the 1997-2004 period, we found that on average approximately 58 Pg C year -1 was fixed by plants as NPP, and approximately 95% of this was returned back to the atmosphere via Rh. Another 4%, or 2.5 Pg C year-1 was emitted by biomass burning; the remainder consisted of losses from fuel wood collection and subsequent burning. At a global scale, burned area and total fire emissions were largely decoupled from year to year. Total carbon emissions tracked burning in forested areas (including deforestation fires in the tropics), whereas burned area was largely controlled by savanna fires that responded to different environmental and human factors. Biomass burning emissions showed large interannual variability with a range of more than 1 Pg C year-1, with a maximum in 1998 (3.2 Pg C year -1) and a minimum in 2000 (2.0 Pg C year-1).
• Van, G., Randerson, J. T., Giglio, L., Collatz, G. J., Kasibhatla, P. S., & Arellano Jr., A. F. (2006). Interannual variability in global biomass burning emissions from 1997 to 2004. Atmospheric Chemistry and Physics, 6(11), 3423-3441.
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  Abstract: Biomass burning represents an important source of atmospheric aerosols and greenhouse gases, yet little is known about its interannual variability or the underlying mechanisms regulating this variability at continental to global scales. Here we investigated fire emissions during the 8 year period from 1997 to 2004 using satellite data and the CASA biogeochemical model. Burned area from 2001-2004 was derived using newly available active fire and 500 m. burned area datasets from MODIS following the approach described by Giglio et al. (2006). ATSR and VIRS satellite data were used to extend the burned area time series back in time through 1997. In our analysis we estimated fuel loads, including organic soil layer and peatland fuels, and the net flux from terrestrial ecosystems as the balance between net primary production (NPP), heterotrophic respiration (Rh), and biomass burning, using time varying inputs of precipitation (PPT), temperature, solar radiation, and satellite-derived fractional absorbed photosynthetically active radiation (fAPAR). For the 1997-2004 period, we found that on average approximately 58 Pg C year -1 was fixed by plants as NPP, and approximately 95% of this was returned back to the atmosphere via Rh. Another 4%, or 2.5 Pg C year-1 was emitted by biomass burning; the remainder consisted of losses from fuel wood collection and subsequent burning. At a global scale, burned area and total fire emissions were largely decoupled from year to year. Total carbon emissions tracked burning in forested areas (including deforestation fires in the tropics), whereas burned area was largely controlled by savanna fires that responded to different environmental and human factors. Biomass burning emissions showed large interannual variability with a range of more than 1 Pg C year-1, with a maximum in 1998 (3.2 Pg C year -1) and a minimum in 2000 (2.0 Pg C year-1).
• Arellano Jr., A. F., Kasibhatla, P. S., Giglio, L., R., G., & Randerson, J. T. (2004). Top-down estimates of global CO sources using MOPITT measurements. Geophysical Research Letters, 31(1), L01104 1-5.
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  Abstract: We present a synthesis inversion of CO emissions from various geographical regions and for various source categories for the year 2000 using CO retrievals from the MOPITT (Measurements of Pollution in the Troposphere) instrument. We find a large discrepancy between our top-down estimates and recent bottom-up estimates of CO emissions from fossil fuel/biofuel (FFBF) use in Asia. A key conclusion of this study is that CO emissions in East Asia (EAS) are about a factor of 1.8-2 higher than recent bottom-up estimates. Copyright 2004 by the American Geophysical Union.
• Arellano, A. F., Kasibhatla, P. S., Giglio, L., van der Werf, G. R., & Randerson, J. T. (2004). Top-down estimates of global CO sources using MOPITT measurements. Geophysical Research Letters, 31(Issue 1). doi:10.1029/2003gl018609
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  We present a synthesis inversion of CO emissions from various geographical regions and for various source categories for the year 2000 using CO retrievals from the MOPITT (Measurements of Pollution in the Troposphere) instrument. We find a large discrepancy between our top-down estimates and recent bottom-up estimates of CO emissions from fossil fuel/biofuel (FFBF) use in Asia. A key conclusion of this study is that CO emissions in East Asia (EAS) are about a factor of 1.8-2 higher than recent bottom-up estimates. Copyright 2004 by the American Geophysical Union.
• R., G., Randerson, J. T., Collatz, G. J., Giglio, L., Kasibhatla, P. S., Arellano Jr., A. F., Olsen, S. C., & Kasischke, E. S. (2004). Continental-Scale Partitioning of Fire Emissions during the 1997 to 2001 El Niño/La Niña Period. Science, 303(5654), 73-76.
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  PMID: 14704424;Abstract: During the 1997 to 1998 El Niño, drought conditions triggered widespread increases in fire activity, releasing CH4 and CO 2 to the atmosphere. We evaluated the contribution of fires from different continents to variability in these greenhouse gases from 1997 to 2001, using satellite-based estimates of fire activity, biogeochemical modeling, and an inverse analysis of atmospheric CO anomalies. During the 1997 to 1998 El Niño, the fire emissions anomaly was 2.1 ± 0.8 petagrams of carbon, or 66 ± 24% of the CO2 growth rate anomaly. The main contributors were Southeast Asia (60%), Central and South America (30%), and boreal regions of Eurasia and North America (10%).
• Van Der Werf, G. R., Randerson, J. T., Collatz, G. J., Giglio, L., Kasibhatla, P. S., Arellano, A. F., Olsen, S. C., & Kasischke, E. S. (2004). Continental-Scale Partitioning of Fire Emissions during the 1997 to 2001 El Niño/La Niña Period. Science, 303(Issue 5654). doi:10.1126/science.1090753
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  During the 1997 to 1998 El Niño, drought conditions triggered widespread increases in fire activity, releasing CH4 and CO 2 to the atmosphere. We evaluated the contribution of fires from different continents to variability in these greenhouse gases from 1997 to 2001, using satellite-based estimates of fire activity, biogeochemical modeling, and an inverse analysis of atmospheric CO anomalies. During the 1997 to 1998 El Niño, the fire emissions anomaly was 2.1 ± 0.8 petagrams of carbon, or 66 ± 24% of the CO2 growth rate anomaly. The main contributors were Southeast Asia (60%), Central and South America (30%), and boreal regions of Eurasia and North America (10%).
• Koe, L. C., Arellano, A. F., & McGregor, J. L. (2003). Application of DARLAM to regional haze modeling. Pure and Applied Geophysics, 160(Issue 1-2). doi:10.1007/s00024-003-8772-9
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  The CSIRO Division of Atmospheric Research limited area model (DARLAM) is applied to atmospheric transport modeling of haze in southeast Asia. The 1998 haze episode is simulated using an emission inventory derived from hotspot information and adopting removal processes based on SO2. Results show that the model is able to simulate the transport of haze in the region. The model images closely resemble the plumes of NASA Total Ozone Mapping Spectrometer and Meteorological Service Singapore haze maps. Despite the limitation of input data, particularly for haze emissions, the three-month average pattern correlation obtained for the whole episode is 0.61. The model has also been able to reproduce the general features of transboundary air pollution over a long period of time. Predicted total particulate matter concentration also agrees reasonably well with observation. The difference in the model results from the satellite images may be attributed to the large uncertainties of emission, simplification of haze deposition and transformation mechanisms and the relatively coarse horizontal and vertical resolution adopted for this particular simulation.
• Koe, L. C., F., A., & McGregor, J. L. (2003). Application of DARLAM to regional haze modeling. Pure and Applied Geophysics, 160(1-2), 189-204.
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  Abstract: The CSIRO Division of Atmospheric Research limited area model (DARLAM) is applied to atmospheric transport modeling of haze in southeast Asia. The 1998 haze episode is simulated using an emission inventory derived from hotspot information and adopting removal processes based on SO2. Results show that the model is able to simulate the transport of haze in the region. The model images closely resemble the plumes of NASA Total Ozone Mapping Spectrometer and Meteorological Service Singapore haze maps. Despite the limitation of input data, particularly for haze emissions, the three-month average pattern correlation obtained for the whole episode is 0.61. The model has also been able to reproduce the general features of transboundary air pollution over a long period of time. Predicted total particulate matter concentration also agrees reasonably well with observation. The difference in the model results from the satellite images may be attributed to the large uncertainties of emission, simplification of haze deposition and transformation mechanisms and the relatively coarse horizontal and vertical resolution adopted for this particular simulation.
• Kasibhatla, P., Arellano, A., Logan, J. A., Palmer, P. I., & Novelli, P. (2002). Top-down estimate of a large source of atmospheric carbon monoxide associated with fuel combustion in Asia. Geophysical Research Letters, 29(19), 6-1.
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  Abstract: Deriving robust regional estimates of the sources of chemically and radiatively important gases and aerosols to the atmosphere is challenging. Here, we focus on carbon monoxide. Using an inverse modeling methodology, we find that the source of carbon monoxide from fossil-fuel and biofuel combustion in Asia during 1994 was 350-380 Tg yr-1, which is 110-140 Tg yr-1 higher than bottom-up estimates derived using traditional inventory-based approaches. This discrepancy points to an important gap in our understanding of the human impact on atmospheric chemical composition.
• Kasibhatla, P., Arellano, A., Logan, J. A., Palmer, P. I., & Novelli, P. (2002). Top-down estimate of a large source of atmospheric carbon monoxide associated with fuel combustion in Asia. Geophysical Research Letters, 29(Issue 19). doi:10.1029/2002gl015581
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  Deriving robust regional estimates of the sources of chemically and radiatively important gases and aerosols to the atmosphere is challenging. Here, we focus on carbon monoxide. Using an inverse modeling methodology, we find that the source of carbon monoxide from fossil-fuel and biofuel combustion in Asia during 1994 was 350-380 Tg yr-1, which is 110-140 Tg yr-1 higher than bottom-up estimates derived using traditional inventory-based approaches. This discrepancy points to an important gap in our understanding of the human impact on atmospheric chemical composition.
• Koe, L. C., Arellano Jr., A. F., & McGregor, J. L. (2001). Investigating the haze transport from 1997 biomass burning in Southeast Asia: Its impact upon Singapore. Atmospheric Environment, 35(15), 2723-2734.
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  Abstract: The 1997 Indonesia forest fires was an environmental disaster of exceptional proportions. Such a disaster caused massive transboundary air pollution and indiscriminate destruction of biodiversity in the world. The immediate consequence of the fires was the production of large amounts of haze in the region, causing visibility and health problems within Southeast Asia. Furthermore, fires of these magnitudes are potential contributors to global warming and climate change due to the emission of large amounts of greenhouse gases and other pyrogenic products.The long-range transport of fire-related haze in the region is investigated using trajectories from the CSIRO Division of Atmospheric Research Limited Area Model (DARLAM). Emission scenarios were constructed for hotspot areas in Sumatra and Kalimantan for the months of September and October 1997 to determine the period and fire locations most critical to Singapore. This study also examines some transport issues raised from field observations. Results show that fires in the coastal areas of southeast Sumatra and southwest Kalimantan can be potential contributors to transboundary air pollution in Singapore. Singapore was directly affected by haze from these areas whereas Kuala Lumpur was heavily affected by the haze coming from Sumatra. In most cases, Singapore was more affected by fires from Kalimantan than was Kuala Lumpur. This was mainly a result of the shifting of monsoons. The transition of monsoons resulted in weaker low-level winds and shifted convergence zones near to the southeast of Peninsular Malaysia. In addition to severe drought and massive fire activity in 1997, the timing of the monsoon transition has a strong influence on haze transport in the region. Copyright © 2001 Elsevier Science Ltd.
• Koe, L. C., Arellano, A. F., & McGregor, J. L. (2001). Investigating the haze transport from 1997 biomass burning in Southeast Asia: Its impact upon Singapore. Atmospheric Environment, 35(Issue 15). doi:10.1016/s1352-2310(00)00395-2
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  The 1997 Indonesia forest fires was an environmental disaster of exceptional proportions. Such a disaster caused massive transboundary air pollution and indiscriminate destruction of biodiversity in the world. The immediate consequence of the fires was the production of large amounts of haze in the region, causing visibility and health problems within Southeast Asia. Furthermore, fires of these magnitudes are potential contributors to global warming and climate change due to the emission of large amounts of greenhouse gases and other pyrogenic products.The long-range transport of fire-related haze in the region is investigated using trajectories from the CSIRO Division of Atmospheric Research Limited Area Model (DARLAM). Emission scenarios were constructed for hotspot areas in Sumatra and Kalimantan for the months of September and October 1997 to determine the period and fire locations most critical to Singapore. This study also examines some transport issues raised from field observations. Results show that fires in the coastal areas of southeast Sumatra and southwest Kalimantan can be potential contributors to transboundary air pollution in Singapore. Singapore was directly affected by haze from these areas whereas Kuala Lumpur was heavily affected by the haze coming from Sumatra. In most cases, Singapore was more affected by fires from Kalimantan than was Kuala Lumpur. This was mainly a result of the shifting of monsoons. The transition of monsoons resulted in weaker low-level winds and shifted convergence zones near to the southeast of Peninsular Malaysia. In addition to severe drought and massive fire activity in 1997, the timing of the monsoon transition has a strong influence on haze transport in the region. Copyright © 2001 Elsevier Science Ltd.

Proceedings Publications

• Gaubert, B., Mirrezaei, M. A., Arellano, A. F., Fernandez, R. P., Ortega, I., Feng, C., Xu, Y., & Saiz-Lopez, A. (2025). Role of Atmospheric Chemistry in Monitoring Changes in the CH 4 Budget, Investigating the Role of Chemical Feedback. In 105th AMS Annual Meeting.
• Gaubert, B., Mirrezaei, M. A., Arellano, A., Fernandez, R., Ortega, I., Emmons, L., Roozitalab, B., Bruhwiler, L., Oh, Y., Lan, X., Petron, G., McKain, K., Saez-Lopez, A., Cuevas, C., Feng, C., Xu, Y., & Brasseur, G. (2025).

  Role of atmospheric chemistry in monitoring changes in the CH₄ Budget

  . In AGU Fall Meeting 2025.
• Mirrezaei, M. A., Gaubert, B., Ortega, I., McKain, K., Bruhwiler, L., Oh, Y., Saez-Lopez, A., Fernandez, R., Saunois, M., Emmons, L., & Arellano, A. (2025).

  Constraining the Global Methane Sink through Joint Assimilation of CH₄ and CO

  . In AGU Fall Meeting 2025.
• Mirrezaei, M. A., Tang, W., Gaubert, B., Emmons, L. K., Guo, Y., Roychoudhury, C., & Arellano, A. F. (2025). Can Global Chemistry-Climate Models Capture Salient Features of an Urban Atmosphere?. In 105th AMS Annual Meeting.
• Pan, K., Arellano, A. F., Tangborn, A., Carroll, B., Demoz, B., & Santanello, J. A. (2025). Assimilation of Doppler Lidar-Derived Planetary Boundary Layer Heights Using the Ensemble Kalman Filter During the PECAN Field Campaign. In 105th AMS Annual Meeting.
• Risanto, C. B., Arellano Jr., A. F., Koch, S., Castro, C. L., Shohan, S., & Adams, D. K. (2025). Improving Monsoon Precipitation Forecast Accuracy over Complex Terrain in Arizona with GPS-PWV Data Assimilation. In EGU General Assembly 2025.
• Risanto, C. B., Arellano, A. F., Castro, C. L., Koch, S. E., Shohan, S. S., Weckwerth, T. M., Pinto, J. O., & Kay, J. (2024). Assessing the Impact of Data Assimilation and Microphysics Schemes on Monsoon Precipitation Forecasts over Arizona Complex Terrain. In 21st Conference on Mountain Meteorology.
• Shohan, S. S. (2024). Evaluation of Optimal Mesonetwork Design for Monitoring and Predicting North American Monsoon (NAM) Convection Using Observing System Simulation Experiments (OSSE). In 21st Conference on Mountain Meteorology.

Presentations

• Hopstock, K., McClure, C., Kramer, S. J., Hafner, H. R., Fraser, M. P., Herckes, P., Sorooshian, A., Robinson, E., & Arellano, A. F. (2026, January).

  Ground Level Ozone Research (GLOR) Campaign: High-Resolution Measurements of Ozone Precursors in the Phoenix Metropolitan Area

  . 106th AMS Annual Meeting. Houston, Texas.
• Mirrezaei, M. A., Gaubert, B., Ortega, I., McKain, K., Bruhwiler, L., Oh, Y., Saez-Lopez, A., Fernandez, R., Emmons, L., Feng, C., Xu, Y., & Arellano, A. (2025, January).

  Emission-Driven Insights and Multispecies Constraints on Global OH Sinks

  . 106th AMS Annual Meeting. Houston, Texas.
• Arellano, A. F. (2023, January). Elucidating Non-linear Chemical and Aerosol Interactions in Earth System Models. Frontiers in Atmospheric Chemistry Seminar Series. Boston, MA: MIT.
• Arellano, A. F. (2023, March). Challenges and Opportunities in Inverse Modeling: A case with Carbon Monoxide Sources. BIRS Mathematic Approaches of Atmospheric Constituents Data Assimilation and Inverse Modeling. BANFF, Alberta, Canada (presented remotely): BANFF.
• Arellano, A. F., & Gaubert, B. (2023, January). Space-Based Observational and Coupled Model Constraints on Hydroxyl Radical Abundance and Methane Loss,. AMS Annual Meeting. Denver, CO: AMS.
• Furlong, M., & Arellano, A. F. (2023, January). Drift from Agricultural Pesticide Applications During Pre-conception and Pregnancy and Associations with Extremely Preterm Birth in Arizona. AMS Annual Meeting. Denver, CO: AMS.
• Gaubert, B., Tang, W., Emmons, L., Worden, H., Ortega, I., Edwards, D., & Arellano, A. F. (2023). Global ensemble chemical data assimilation to efficiently estimate initial conditions and emissions by source. 9th International Symposium on Non-CO2 Greenhouse Gases (NCGG8). Amsterdam, Netherlands.
• Lorenzi, G., Barth, M., Arellano, A. F., Crosbie, E., Diskin, G., Hilario, M., Tilmes, S., Wang, J., Zhang, J., Ziemba, L., & Sorooshian, A. (2023, January). Aerosol Convective Transport in Southeast Asia: Analysis and Evaluation of Aircraft and Modeled Data. AMS Annual Meeting. Denver, CO: AMS.
• Risanto, C. B., Moker, J., Arellano, A. F., Castro, C., Serra, Y., & Adams, D. (2023, January). On the Importance of Multi-Scale Constraints on Mesoscale Convective System and Precipitation Forecasts over Complex Terrain. AMS Annual Meeting. Denver, CO: AMS.
• Arellano, A. F. (2022, October). Towards the Identification of Emergent Properties in Local-to- Global Air Quality and Greenhouse Gases. CHEE Seminar Series. Tucson, AZ: UA CHEE.
• Arellano, A. F. (2021, March). On the Emergence of a Rise in Anthropogenic Combustion in Sub-Saharan Africa. Advancing Air Quality and Carbon Science in Africa (NCAR). Virtual: NCAR.
• Arellano, A. F. (2021, November). Towards Seamless Prediction of Chemical Weather and Air Quality. Program in Applied Mathematics Seminar Series (City Air and University of Arizona Air Quality Seminar). Virtual: UArizona Applied Mathematics and City Air.
• Arellano, A. F. (2022, January). The Impact of Precipitable Water Vapor Data Assimilation on North American Monsoon Precipitation Forecast in Northern Mexico. RIken Data Assimilation Seminar Series. Kobe, Japan (virtual): RIKEN Center for Computational Science.
• Arellano, A. F., & Gaubert, B. (2022, January). Investigating the Interactions between CH4, CO, and OH from Modeling and Observational Perspectives. American Meteorological Society (AMS) 102nd Annual Meeting: 24th Conference on Atmospheric Chemistry. Virtual: AMS.
• Arellano, A. F., McKinnon, J., Roychoudhury, C., Buccholtz, R., & Gaubert, B. (2021, December). Spatio-temporal Pattern Analysis of Trace Gases and Aerosol Abundance Using PCA, SOMs, and Convolution Auto-encoders. 2021 AGU Fall Meeting. New Orleans, LA: AGU.
• McKinnon, J., Roychoudhury, C., Gaubert, B., Buchholz, R., & Arellano, A. F. (2022, January). Spatiotemporal Pattern Analysis of Trace Gases and Aerosol Abundance over Sub-Saharan Africa Using PCA/CCA and SOMs. American Meteorological Society (AMS) 102nd Annual Meeting: 24th Conference on Atmospheric Chemistry. Virtual: AMS.
• Roychoudhury, C., He, C., Kumar, R., & Arellano, A. F. (2021, September). Exploring the association of meteorology and atmospheric composition to snow cover changes: A case study over High-Mountain Asia and Central Andes. Meteorology and Climate - Modeling for Air Quality Conference (MAC-MAQ). Virtual: UC Davis.
• Roychoudhury, C., He, C., Kumar, R., Shrivastava, M., McKinnon, J., & Arellano, A. F. (2021, December). Model simulations and satellite data analysis of aerosol impacts to snow cover over High Mountain Asia. 2021 AGU Fall Meeting. New Orleans, LA: AGU.
• Arellano, A. F. (2020, December). Observational Constraints of Anthropogenic Combustion from Space: Opportunities for Monitoring Efficiency. 1st International Conference on Innovative Technologies for a Sustainable Environment (ICITSE2020). Virtual Conference: Society of Environmental Engineers of the Philippines, Inc..
• Arellano, A. F. (2020, July). Towards the Identification of Emergent Properties in Atmospheric Composition Using Satellite Data: A Case of Megacity Emissions Monitoring from Space. 40th Anniversary and 2020 Annual Scientific Meeting (APAMS). Virtual Conference: Philippine-American Academy of Science and Engineering.
• Arellano, A. F. (2020, November). Investigating the Human Fingerprints in the Atmosphere: The Role of Remote Sensing and Data Science. UP DMMME Distinguished Alumni Seminar. Virtual Conference: University of the Philippines, Dept. of Mining, Metallurgical, and Materials Engineering.
• Brocchi, V., Mottungan, K., Gaubert, B., Tang, W., & Arellano, A. F. (2021, January). On the Emergence of a Rise in Anthropogenic Combustion in Sub-Saharan Africa. American Meteorological Society (AMS) 101st Annual Meeting. Virtual Conference: AMS.
• Mottungan, K., Arellano, A. F., Brocchi, V., & Gaubert, B. (2020, June). Utilizing the synergies between air quality and greenhouse gas measurements in constraining anthropogenic CO2 and CH4 over Sub-Saharan Africa. International Workshop oOn Greenhouse Gas Measurements from Space (IWGGMS-16). Virtual Conference: ECMWF/EUMETSAT/ESA/EC.
• Risanto, C. B., Castro, C. L., Arellano, A. F., Moker, J. M., & Adams, D. K. (2021, January). The Impact of PWV Data Assimilation in Convective-Permitting WRF-ARW on North American Monsoon Precipitation Forecasts over Northwest Mexico. American Meteorological Society (AMS) 101st Annual Meeting. Virtual Conference: AMS.
• Arellano, A. F. (2019, August). Exploring Multiple Observational and Modeling Constraints on Anthropogenic Pollution over Megacities and Biomass Burning Regions: Opportunities and Challenges in Improving Emissions Inventories. 2019 Panorama Actual De las Ciencias Atmosféricas. National Autonomous University of Mexico (UNAM), Mexico City, Mexico: UNAM.
• Arellano, A. F. (2019, August). Substantiating Key Synergies Between Air Quality (AQ) and Greenhouse Gas (GHG) Monitoring from Space: A case for anthropogenic CO2 and CH4 constraints from CO and NO2. Special Seminar, Dept. of Physics, Univ. of Toronto. Toronto, CA.
• Arellano, A. F. (2019, June). Investigating the Utility of CO2 and CO Analysis in Tracking Fossil Fuel CO2. CEOS AC-VC-15: The 15th Meeting of the Atmospheric Composition Virtual Constellation. Tokyo, Japan: JAXA.
• Arellano, A. F. (2019, September). Towards the Identification of Emergent Properties in Atmospheric Composition using Satellite Data. NCAR Frontiers of Atmospheric Science and Chemistry: Integration of Novel Applications and Technological Endeavors (FASCINATE). Boulder, CO: NCAR.
• Arellano, A. F., Gaubert, B., Miyazaki, K., Inness, A., Jiang, Z., Zheng, B., Flemming, J., & Yin, Y. (2019, June). Trends in Carbon Monoxide Abundance as Inferred from an Ensemble of Chemical Reanalyses and their Implications to Air Quality/Greenhouse Gas Emissions Monitoring. 8th International Symposium on Non-CO2 Greenhouse Gases (NCGG8). Amsterdam, The Netherlands: VVM.
• Brocchi, V., Arellano, A. F., Tang, W., & Gaubert, B. (2019, December). Understanding Anthropogenic Combustion in Major Cities of Africa from Multiple Data Streams. 2019 AGU Fall Meeting. San Francisco: AGU.
• Castro, C. L., Adams, D. K., Arellano, A. F., Quintanar, A. I., Ochoa-Moya, C., Minjarez-Sosa, C. M., Rodriguez, J., Lizarraga, C., Vivoni, E., Perez-Ruiz, E., Robles, A., Risanto, C. B., Chang, H. I., Mendoza-Fierro, L., & Moker, Jr., J. M. (2019, January). A New Hydrometeorological Testbed in Northern Mexico for Improved Weather Forecasts and Climate Monitoring. 99th Annual American Meteorological Society Meeting.
• Castro, C. L., Risanto, C. B., Moker, Jr., J. M., Arellano, A. F., Adams, D. K., & Mendoza-Fierro, L. (2019, January). CAZMEX 2017: Improving Monsoon Precipitation Forecasts in Northwest Mexico and Southwest United States. 99th Annual American Meteorological Society Meeting.
• Arellano, A. F. (2018, July/Summer). Emerging Patterns of O3 Sensitivity to CO over Megacities Derived from Satellite Retrievals. JAMSTEC RCGC/IACE/Big-Data seminar. Yokohama, Japan: JAMSTEC.
• Arellano, A. F. (2018, July/Summer). Observational Constraints of Anthropogenic Combustion from Space: Opportunities for Monitoring Efficiency,. Japan Agency for Marine-Earth Science and Technology Air Quality-Greenhouse Gases (AQ-GHG) Joint Meeting. Tokyo, Japan: JAMSTEC.
• Arellano, A. F. (2018, March/Spring). Impact of Total Column Water Vapor Measurements on Short-to-Medium-Range Forecasts of North American Monsoon Precipitation. InSAR​ ​Meteorology​ ​Workshop. Univ. of Miami, FL: NASA.
• Arellano, A. F. (2018, May/Spring). Observational Constraints of Anthropogenic Combustion from Space: Opportunities for Monitoring Efficiency. Committee on Earth Observation Satellites (CEOS) Atmospheric Composition (AC) Virtual Constellation GEOCAPE Joint Meeting. College Park, MD: CEOS.
• Arellano, A. F., Clerbaux, C., Boynard, A., George, M., Wespes, C., & Hadji-Lazaro, J. (2018, April/Spring). Emerging Patterns of O3 Sensitivity to CO over Megacities Derived from Satellite Retrievals. European Geophysical Union General Assembly. Vienna, Austria: EGU.
• Arellano, A. F., Gaubert, B., Miyazaki, K., Inness, A., Jiang, Z., Zheng, B., Flemming, J., & Yin, Y. (2019, January). Long-term Changes in Carbon Monoxide Abundance as Inferred from an Ensemble of Chemical Reanalysis. AMS 99th Annual Meeting. Phoenix, AZ: AMS.
• Arellano, A. F., Tang, W., & Gaubert, B. (2020, January). Anthropogenic Carbon Emission Constraints from CO and NO2 Data Streams. 22nd Conference on Atmospheric Chemistry/100th AMS Annual Meeting. Boston, MA: AMS.
• Risanto, C. B., Castro, C. L., Arellano, A. F., Fierro, L. M., & Moker, J. M. (2020, January). Forecasting North American Monsoon Precipitation with Data Assimilation. 24th Conference on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface (IOAS-AOLS)/100th AMS Annual Meeting,. Boston, MA: AMS.
• Tang, W., Emmons, L., Arellano, A. F., & Gaubert, B. (2018, June/Summer). CO Source Contributions and Combustion Characteristics during KORUS-AQ. Asia Oceania Geosciences Society (AOGS) Annual Meeting. Honolulu, Hawaii: AOGS.
• Tang, W., Gaubert, B., Arellano, A. F., Emmons, L. K., DiGangi, J., Choi, Y., & Diskin, G. (2018, December/Fall). Tracking Fossil Fuel Emissions in East Asia by Combining Model Simulations, Satellite Observations, and Field Measurements of the CO-to-CO2 Ratio. 2018 American Geophysical Union Fall Meeting. Washington D.C.: AGU.
• Arellano, A. F. (2017, November). On the Nexus Between Carbon Cycle and Air Quality: Exploring Multiple Constraints on Anthropogenic Combustion and Fires. ECMWF Seminar Series. Reading, UK: ECMWF.
• Arellano, A. F. (2017, November). On the Nexus Between Carbon Cycle and Air Quality: Exploring Multiple Constraints on Anthropogenic Combustion and Fires. LATMOS Seminar Series. UPMC, Paris France: LATMOS.
• Arellano, A. F. (2017, September). Confronting Recent Chemical Reanalyses with Satellite Data on Combustion Characteristics Over Megacities,. 18th GEIA Conference. Hamburg, Germany: IGAC/GEIA.
• Arellano, A. F., & Tang, W. (2017, December). Sensitivity of CAM-Chem/DART MOPITT CO Assimilation Performance to the Choice of Ensemble System Configuration: A Case Study for Fires in the Amazon. 2017 AGU Fall Meeting. New Orleans, LA: AGU.
• Arellano, A. F., Tang, W., Silva, S., & Raman, A. (2017, December). Exploring Multiple Constraints of Anthropogenic Pollution. 2017 AGU Fall Meeting. New Orleans, LA: AGU.
• Arellano, A. F., Tang, W., Silva, S., & Raman, A. (2018, January). Exploring Multiple Constraints of Anthropogenic Pollution in Combustion Regions from Current Satellite Retrievals of Atmospheric Composition. 20th Conference on Atmospheric Chemistry, AMS 98th Annual Meeting. Austin, Texas: AMS.
• Choi, Y., DiGangi, J., Diskin, G., Novak, J., Halliday, H., Pushed, S., Arellano, A. F., Tang, W., Knote, C., Woo, J., Lee, Y., Bu, C., Blake, D., Simpson, I., Blake, N., & Xu, X. (2017, December). Atmospheric Observations of Carbon Dioxide and Quantification of Fossil Fuel Carbon Dioxide and Emission Inventories using Radiocarbon in the Korean Peninsula during the KORUS-AQ Field Campaign. 2017 AGU Fall Meeting. New Orleans, LA: AGU.
• Gaubert, B., Emmons, L., Miyazaki, K., Buchholz, R., Tang, W., Arellano, A. F., Tilmes, S., Barre, J., Worden, H., Raeder, K., Anderson, J., & Edwards, D. (2017, December). Diagnostics of sources of tropospheric ozone using data assimilation during the KORUS-AQ campaign. 2017 AGU Fall Meeting. New Orleans, LA: AGU.
• Smith, W. K., Arellano, A. F., Barnes, M. L., Hudson, A. R., Montane, F., Fox, A. M., & Moore, D. J. (2017, Aug). Combining models and data to understand vegetation function across timescales. 102nd Annual Meeting of the Ecological Society of America. Portland, OR: ESA.
• Arellano, A. F. (2016, April). Data Assimilation for Monsoon Hydrometeorological Studies. UC-MEXUS Meeting.
• Arellano, A. F. (2016, August). Air Quality Data Assimilation: Methods Part 1. NCAR Advance Study Program Summer Colloquium on Advances in Air Quality Analysis and Prediction: The Interaction of Science and Policy.
• Arellano, A. F. (2016, August). Emission Estimation- State Augmentation. NCAR Advance Study Program Summer Colloquium on Advances in Air Quality Analysis and Prediction: The Interaction of Science and Policy.
• Arellano, A. F., Raman, A., Brost, J., & Sorooshian, A. (2016, December). Modeling and observations of dust aerosols during the North American Monsoon. AGU 2016 Fall Meeting.
• Edwards, D., Barre, J., Worden, H., & Arellano, A. F. (2016, September). Quantifying wildfire emissions and associated aerosols species using assimilation of satellite carbon monoxide retrievals. 2016 International Global Atmospheric Chemistry (IGAC) Project Science Conference.
• Raman, A., Arellano, A. F., & Kuma, R. (2016, December). Estimating black carbon concentrations from combustion tracers: synergistic perspective using in-situ measurements, multi-satellite retrievals, and chemical transport model. AGU 2016 Fall Meeting.
• Arellano, A. F. (2015, December). Inverse Modeling of BC and CO Sources in WRF-Chem. 2015 AGU Fall Meeting. San Francisco, CA: AGU.
• Arellano, A. F. (2015, June). Data Assimilation in the NAM Region: Challenges and Opportunities. 3rd Meeting of Regional Meteorology Climatology and Northwest Mexico. Universidad Nacional Autónoma de México, Mexico City: UNAM.
• Arellano, A. F. (2015, November). Top-down Estimates of Combustion Characteristics Over Megacities and Major Fire Regions. 17th GEIA: Global Emissions Initiative Conference (Influence of Urbanization on Emissions Worldwide). Tsinghua University, Beijing China: GEIA.
• Arellano, A. F. (2015, October). Towards Seamless Prediction of Chemical Weather. UA GIDP Statistics Collquium. Tucson, AZ: GIDP Statistics.
• Knote, C., Barre, J., Eckl, M., Hornbrook, R., Wiedinmyer, C., Emmons, L., Orlando, J., Tyndall, G., & Arellano, A. F. (2015, December). Inferring the unobserved chemical state of the atmosphere: idealized data assimilation experiments. 2015 AGU Fall Meeting. San Francisco, CA: AGU.
• Tang, W., Arellano, A. F., Raman, A., & Deeter, M. (2015, April). A Comparative Analysis on the Temporal and Spatial Distribution of Fire Characteristics in the Amazon and Equatorial Southern Africa Using Observations from Space. 2015 EGU Meeting. Vienna, Austria: EGU.
• Arellano, A. F., & Silva, S. (2014, April). Combustion signatures as seen from space: Implications for tracking anthropogenic CO2. OCO-2 Applications Workshop. Maryland, MD: NASA.
• Barre, J., Edwards, D., Arellano, A. F., Gaubert, B., Worden, H., Anderson, J., & Mizzi, A. (2014, December). Assessment of IASI CO and MOPITT CO Data Assimilation in CAM-Chem. 2014 AGU Fall Meeting. San Francisco, CA: AGU.
• Barre, J., Gaubert, B., Arellano, A. F., Worden, H., Edwards, D., Tilmes, S., Collins, N., Raeder, K., & Mizzi, A. (2014, August). Multivariate chemical data assimilation and chemistrydynamics interaction. World Weather Open Science 2014. Montreal, Canada: WMO.
• Edwards, D., Barre, J., Worden, H., Arellano, A. F., Gaubert, B., Anderson, J., & Mizzi, A. (2014, December). The atmospheric composition geostationary satellite constellation for air quality and climate science: Evaluating performance with Observation System Simulation Experiments. 2014 AGU Fall Meeting. San Francisco, CA: AGU.
• Gaubert, B., Arellano, A. F., Barre, J., Worden, H., Emmons, L., Wiedinmyer, C., Anderson, J., Mizzi, A., & Edwards, D. (2014, December). Optimizing global CO concentrations and emissions based on DART/CAM-CHEM. 2014 AGU Fall Meeting. San Francisco, CA: AGU.
• Gaubert, B., Barre, J., Worden, H., Edwards, D., Emmons, L., Tilmes, S., Mizzi, A., Arellano, A. F., Anderson, J., & Collins, N. (2014, August). Global CO data assimilation for emissions and trends analysis. World Weather Open Science 2014. Montreal, Canada: WMO.
• Mizzi, A., Arellano, A. F., Edwards, D., Anderson, J., & Barre, J. (2014, August). Ensemble Kalman Filter Assimilation of MOPITT CO Retrieval Profiles with WRF/Chem-DART. World Weather Open Science 2014. Montreal, Canada: WMO.
• Raman, A., Arellano, A. F., & Kumar, R. (2014, June). Quantifying regional emissions using WRF-Chem tagged tracers: Implications for cross-state pollution transport and extreme air quality events. 15th Annual WRF Users' Workshop. Boulder, CO: NCAR.
• Raman, A., Arellano, A. F., & Kumar, R. (2014, September). Using chemical ratios to disentangle sources of particulate matter pollution: Implications for population exposure and mortality. International Global Atmospheric Chemistry (IGAC) Science Conference on Atmospheric Chemistry. Natal, Brazil: IGAC.
• Silva, S., Arellano, A. F., & Worden, H. (2014, May). Exploring the utility of satellite-based CO2/CO and CO2/NO2 sensitivities over urban regions and point sources as constraints on anthorpogenic combustion. International Workshop on Greenhouse Gas Measurements from Space (IWGGMS-9). Noordwijk, The Netherlands: European Space Agency.
• Arellano, A. F. (2013, March). Towards Seamless Prediction of Chemical Weather. Alaska Weather Symposium. Fairbanks, AK: University of Alaska.
• Arellano, A. F. (2013, March). Towards Seamless Prediction of Chemical Weather. UA Applied Mathematics SIAM Student Chapter Seminar. Tucson, AZ: University of Arizona.
• Arellano, A. F. (2013, September). Towards Seamless Prediction of Atmospheric Composition Using Ensemble-based Data Assimilation. Biennial Air Quality Research Center Conference on Traversing New Terrain in Meteorological Modeling, Air Quality, and Dispersion. Davis, CA: AMS.
• Arellano, A. F., Raman, A., & Chatterjee, A. (2015, January). Comparison of algorithms for assimilating satellite partial column retrievals from MOPITT and IASI with WRF-Chem/DART. AMS 95th Annual Meeting. Phoenix, Arizona: AMS.
• Mizzi, A., Arellano, A. F., Edwards, D., Anderson, J., & Barre, J. (2014, February). An efficient algorithm for assimilation of satellite retrieval profiles of chemical trace gases in the troposphere with the DART ensemble Kalman filter in WRFCHEM. AMS 94th Annual Meeting. Atlanta, GA: AMS.
• Moker, J., Serra, Y., Castro, C., & Arellano, A. F. (2015, January). Impact of Precipitable Water on Forecasting the 2013 North American Monsoon. AMS 95th Annual Meeting. Phoenix, Arizona: AMS.
• Raman, A., & Arellano, A. F. (2013, June). A WRF/CHEM sensitivity study towards high resolution air qualityforecasting for southwestern United States. 14th Annual WRF Users' Workshop. Boulder, CO: NCAR.
• Rosolem, R., Hoar, T., Arellano, A. F., Anderson, J., Shuttleworth, W., Zeng, X., & Franz, T. (2014, December). Translating above-ground cosmic-ray neutron intensity to high-frequency soil moisture profile at sub-kilometer scale. 2014 AGU Fall Meeting. San Francisco, CA: AGU.
• Silva, S., & Arellano, A. F. (2013, May). Patterns of CO2 Sensitivity to CO from Space and their Implications for Carbon Monitoring. International Workshop on Greenhouse Gas Measurements from Space (IWGGMS-9). Yokohama, Japan: JAXA.

Poster Presentations

• Beran, B. G., Siu, L. W., Choi, Y., Diskin, G., Thornhill, K., Pan, K., Arellano, A. F., & Sorooshiaqn, A. (2026, January).

  High-altitude Ozone Intrusions Over the Northwest Atlantic: Lessons Learned During the ACTIVATE Airborne Mission

  . 106th AMS Annual Meeting. Houston, Texas.
• Mirrezaei, M. A., Arellano, A. F., & Furlong, M. (2026, January).

  Long-term Modeling Assessment of Pesticide Spray Drift in Yuma County, Arizona

  . 106th AMS Annual Meeting. Houston, Texas.
• Pan, K., Roychoudhury, C., Beran, B. G., Chouza, F., Leblanc, T., Fraser, M., Herckes, P., Sorooshian, A., & Arellano, A. F. (2026, January).

  A Stratospheric Intrusion Event Contributing to Elevated Surface Ozone Over the Phoenix Metropolitan Region in June 2025

  . 106th AMS Annual Meeting. Houston, Texas.
• Pan, K., Tangborn, A., Anderson, J., Santanello, J., Carroll, B., Demoz, B., & Arellano, A. F. (2026, January).

  Data Assimilation of Planetary Boundary Layer-related Measurements: A Coupled-DA Approach Using Ensemble Kalman Filter

  . 106th AMS Annual Meeting. Houston, Texas.
• Pandey, S., Roots, M., Pan, K., Demoz, B., Arellano, A. F., & Carroll, B. (2026, January).

  Interactions Between Low-Level Jets and Nocturnal Boundary Layer Processes over the Southern Great Plains: Insights from PECAN Observations and WRF Simulations

  . 106th AMS Annual Meeting. Houston, Texas.
• Robinson, M., Roychoudhury, C., Mirrezaei, M. A., Pan, K., Sorooshian, A., & Arellano, A. F. (2026, January).

  Diurnal and Seasonal Variability of Ozone Precursors Across Arizona’s Sun Corridor

  . 106th AMS Annual Meeting. Houston, Texas.
• Roychoudhury, C., Mirrezaei, M. A., Pan, K., Guo, Y., Sorooshian, A., Robinson, E., Fraser, M., Herckes, P., & Arellano, A. F. (2026, January).

  Towards Constraining VOC Emissions over Phoenix during the 2025 GLOR Campaign with Ensemble Models

  . 106th AMS Annual Meeting. Houston, Texas.
• Ajayi, T., Mirrezaei, S., Arellano, A. F., & Sorooshian, A. (2024, December).

  An Examination of the Weekly Periodicity of Surface Ozone Concentrations in Tucson, Arizona, Including Relationships with Monsoon Characteristics

  . AGU Fall Meeting. Washington DC.
• Gaubert, B., Mirrezaei, S., Arellano, A. F., Ortega, I., McKain, K., Bruhwiler, L., Oh, Y., Saez-Lopez, A., Fernandez, R., Saunois, M., Fang, C., Xu, Y., Emmons, L., & Worden, H. (2024, December).

  Investigating the impact of chemical feedback in global transient simulations driven by methane emissions

  . AGU Fall Meeting. Washington DC.
• Guo, Y., Arellano, A. F., Mirrezaei, S., & Sorooshian, A. (2024, December). Source contribution to ozone pollution during June 2021 wildfire season in Arizona: Insights from WRF-Chem tagged O₃ and CO. AGU Fall Meeting. Washington DC.
• McKinnon, J., Arellano, A. F., Roychoudhury, C., & Gaubert, B. (2024, September).

  Analysis of the seasonal variability of atmospheric composition using SSA, EOF, and Fourier Analysis

  . IGAC. Kuala Lumpur.
• McKinnon, J., Roychoudhury, C., Arellano, A. F., & Gaubert, B. (2024, December). Use of power spectral analysis to show correlations between the dominant time scale and chemical lifetime of greenhouse gases and trace gases. AGU Fall Meeting. Washington DC.
• Mirrezaei, M. A., Gaubert, B., & Arellano, A. F. (2024, January). Simulating CH₄ Lifetime and Abundance using the Global Carbon Project CH₄ flux estimates. 104th AMS Annual Meeting. Baltimore, MD: AMS.
• Mirrezaei, S., Gaubert, B., Ortega, I., McKain, K., Bruhwiler, L., Oh, Y., Saez-Lopez, A., Fernandez, R., Saunois, M., Emmons, L., Worden, H., Fang, C., Xu, Y., & Arellano, A. F. (2024, December). Constraining Tropospheric Hydroxyl Radical (OH) Using Emission-Driven CAM-Chem Simulations with Short-Lived Halogen Representation. AGU Fall Meeting. Washington DC.
• Mohammad, A., Mirrezaeri, S., Roychoudhury, C., & Arellano, A. F. (2024, December). Analysis of Air Quality Trends in Kuwait from 2015 to 2022. AGU Fall Meeting. Washington, DC: AGU.
• Pan, K., Arellano, A. F., Demoz, B., Santanello, J., & Blumberg, W. (2024, December). Assimilation of Planetary Boundary Layer Height Measurements with Multi-Physics using Ensemble Kalman Filter During the PECAN Field Campaign. AGU Fall Meeting. Washington DC.
• Pandey, S., Boots, M., Pan, K., Demoz, B., Arellano, A. F., & Caroll, B. (2024, December).

  Understanding PBL Dynamics and Thermodynamics in LLJ events over PECAN: Modeled and Observation

  . AGU Fall Meeting.
• Parakkat, L., Betito, G., Hilario, M., Arellano, A. F., & Sorooshian, A. (2024, December).

  Factors Coinciding with Extreme Events of Ozone Over Rural and Urban Sites in Arizona

  . AGU Fall Meeting. Washington DC.
• Robertson, M., Roychoudhury, C., Mirrezaei, M. A., McKinnon, J. M., Sorooshian, A., & Arellano, A. F. (2024). Assessing Uncertainties in Satellite Data on Arizona's Atmospheric Composition: Insights from Ground-Based Observations from AERONET and PANDORA. AGU24.
• Roychoudhury, C., & Arellano, A. F. (2024, December). Diagnosing Interactions at the Earth System Interface: Case Studies from Snowmelt and Chemical Feedbacks. AGU Fall Meeting. Washington DC.
• Roychoudhury, C., Arellano, A. F., Cheng, W., Mizukami, N., He, C., & Kumar, R. (2024, September).

  Is traditional Bayesian inversion sufficient to constrain black carbon abundance in High Mountain Asia?

  . IGAC.
• Roychoudhury, C., McKinnon, J., Mirrezaei, S., Guo, Y., & Arellano, A. F. (2024, December). Source attribution of wildfires in Arizona: An exploration of the June 2021 wildfire season. AGU Fall Meeting. Washington DC.
• Guo, Y., Arellano, A. F., Roychoudhury, C., Sorooshian, A., Kumar, R., & Pfister, G. (2023, January). Harnessing our Air Quality Modeling & Observational Capabilities to Establish Key Factors Influencing Ozone Levels in Arizona. AMS Annual Meeting. Denver, CO: AMS.
• Guo, Y., Arellano, A. F., Roychoudhury, C., Sorooshian, A., Kumar, R., & Pfister, G. (2023, September). Harnessing our Air Quality Modeling & Observational Capabilities to Establish Key Factors Influencing Ozone Levels in Arizona. Meteorology and Climate – Modeling for Air Quality Conference (MAC-MAQ). UC Davis.
• McKinnon, J., Roychoudhury, C., & Arellano, A. F. (2023, June). se of Covariance Discrimination Analysis to Determine Structural Bias in Modeled Carbon Monoxide. Global Emissions Initiative (GEIA) 20th Conference. Brussels, Belgium: International Global Atmospheric Chemistry.
• Mirrezaei, M. A., Gaubert, B., Fernandez, R. P., Kinnison, D. E., Ortega, I., & Arellano, A. F. (2023, December). Exploring the Variability of CH4 Abundance due to Uncertainties in CH4 Emissions and Chemistry. AGU Fall Meeting. San Francisco: AGU.
• Mirrezaei, M. A., Guo, Y., Roychoudhury, C., Sorooshian, A., Arellano, A. F., Tang, W., & Emmons, L. (2023, September). Investigating surface ozone sensitivity to HCHO/NO2 ratios over Arizona using the Multi-Scale Infrastructure for Chemistry and Aerosols (MUSICA) model. Meteorology and Climate – Modeling for Air Quality Conference (MAC-MAQ). UC Davis.
• Mirrezaei, M. A., Tang, W., Emmons, L., Guo, Y., Gaubert, B., & Arellano, A. F. (2023, December). The impact of horizontal resolution, chemistry, and emissions on surface ozone concentration using Multi-Scale Infrastructure for Chemistry and Aerosols (MUSICAv0). AGU Fall Meeting. San Francisco: AGU.
• Pan, K., & Arellano, A. F. (2023, January). Uncertainties of Modeled and Observed PBL Heights During the PECAN Field Campaign. AMS Annual Meeting. Denver, CO: AMS.
• Roychoudhury, C., Cheng, W., He, C., Kumar, R., & Arellano, A. F. (2023, December). MATCHA, Model for Atmospheric Transport and Chemistry in Asia: A novel regional climate-chemical reanalysis. AGU Fall Meeting. San Francisco: AGU.
• Roychoudhury, C., Cheng, W., He, C., Kumar, R., McKinnon, J., & Arellano, A. F. (2023, December). How uncertain are BC emissions in High Mountain Asia? An inverse modeling approach. AGU Fall Meeting. San Francisco: AGU.
• McKinnon, J., Roychoudhury, C., Arellano, A. F., & Gaubert, B. (2022, December). Spatiotemporal Pattern Analysis of Trace Gases and Aerosol Abundance Using Varimax Rotation. AGU Fall Meeting. Chicago, IL: AGU.
• Pan, K., & Arellano, A. F. (2022, December). Exploring the Range of Uncertainties of Modeled and Observed PBL Heights During the PECAN Field Campaign. AGU Fall Meeting. Chicago, IL: AGU.
• Roychoudhury, C., He, C., Kumar, R., McKinnon, J., & Arellano, A. F. (2022, December). Tracing the sources of black carbon deposition over the glaciers in High Mountain Asia: A tagged- tracer approach using WRF-Chem . AGU Fall Meeting. Chicago, IL: AGU.
• Roychoudhury, C., He, C., Kumar, R., McKinnon, J., & Arellano, A. F. (2022, September). Source attribution of aerosol impacts to snow cover over High Mountain Asia. International Global Atmospheric Chemistry (IGAC) Project Science Conference. Manchester, UK: IGAC.
• Knickrehm, L., Yuan, S., Roychoudhury, C., Arellano, A. F., & Furlong, M. (2022, January). An Ensemble Approach in Modeling the Atmospheric Dispersion of Pesticide Spray Drift in Yuma County. American Meteorological Society (AMS) 102nd Annual Meeting: 22nd Joint Conference on the Applications of Air Pollution Meteorology with the A&WMA. Virtual: AMS.
• Roychoudhury, C., He, C., Kuman, R., & Arellano, A. F. (2021, September). Investigating the relationship of meteorology and atmospheric composition to snow cover: A comparative study over High-Mountain Asia and Ande. 2021 International Global Atmospheric Chemistry (IGAC) Project Science Conference. Virtual: IGAC.
• Mottungan, K., Arellano, A. F., Gaubert, B., DiGangi, J., Choi, Y., & Diskin, G. (2021, January). Characterizing the urban emission signatures of CO, CO2 and CH4 over Southeast Asia during CAMP2EX. American Meteorological Society (AMS) 101st Annual Meeting. Virtual Conference: AMS.
• Arellano, A. F., Tang, W., Gaubert, B., Choi, Y., DiGangi, J., & Diskin, G. (2019, December). Assessing the Utility of CO2:CO Correlations in Improving Top-down Estimates of Fossil-fuel CO2 Emissions. 2019 AGU Fall Meeting. San Francisco, CA: AGU.
• Arellano, A. F., Gaubert, B., Miyazaki, K., Inness, A., Jiang, Z., Yin, Y., & Flemming, J. (2018, December/Fall). Towards a Chemical Inverse Modeling System Experiment: First Results on CO Inter-comparison,. 2018 American Geophysical Union Fall Meeting. Washington, D.C.: AGU.
• Brocchi, V., Arellano, A. F., Tang, W., & Gaubert, B. (2020, January). Impact of African Urban Agglomerations to Global Air Quality,. 22nd Conference on Atmospheric Chemistry/100th AMS Annual Meeting. Boston, MA: AMS.
• Castro, C. L., Moker, Jr., J. M., Serra, Y., Arellano, A. F., & Adams, D. K. (2018, January). Convective-permitting hindcast simulations during the North American monsoon GPS Transect Experiment 2013: Establishing baseline model performance.. 98th Annual American Meteorological Society Meeting.
• Arellano, A. F., Tang, W., Silva, S., Gaubert, B., & Miyazaki, K. (2017, October). Multi-Species Analysis of Anthropogenic Pollution Using IASI Data: Emerging Patterns over Chinese Cities. EUMETSAT Meteorological Conference. Rome, Italy: EUMETSAT.
• Tang, W., & Arellano, A. F. (2017, January). Investigating Combustion and Emission Trends in Megacities through Synthesis of Combustion Signatures Using Multiple Datasets. AMS 2017 Annual Meeting.
• Tang, W., Arellano, A. F., Choi, Y., DiGangi, J., Woo, J., Diskin, G., Agusti-Panareda, A., Parrington, M., Massart, S., Lee, M., Kanaya, Y., Jang, J., Lee, Y., Hong, J., Flynn, J., Thompson, A., & Kim, D. (2017, December). Joint Evaluation of Copernicus Atmosphere Monitoring Service (CAMS) High-resolution Global Near-Real Time CO and CO2 Forecasts during KORUS-AQ Field Campaign. 2017 AGU Fall Meeting. New Orleans, LA: AGU.
• Tang, W., Arellano, A. F., Emmons, L., & Gaubert, B. (2018, January). Ensemble Simulation of Anthropogenic and Biomass Burning CO2 and CO in CAM-chem. 20th Conference on Atmospheric Chemistry, AMS 98th Annual Meeting. Austin, Texas: AMS.
• Deeter, M., Emmons, L., Arellano, A. F., Martinez-Alonso, S., Wiedinmyer, C., Val Martin, M., Gatti, L., Miller, J., Gloor, M., Domingues, L., & Carvalho-Correia, C. (2016, December). Towards Improved MOPITT-based Biomass Burning Emission Inventories for the Amazon Basin. AGU 2016 Fall Meeting.
• Gaubert, B., Barre, J., Arellano, A. F., Worden, H., Emmons, L., Tilmes, S., Martinez-Alonso, S., Anderson, J., & Edwards, D. (2016, December). Overview of the NCAR-MOPITT reanalysis, investigation of chemical error correlations. AGU 2016 Fall Meeting.
• Gaubert, B., Worden, H., Arellano, A. F., Barre, J., Emmons, L., Tilmes, S., Bucholz, R., Anderson, J., Martinez-Alonso, S., & Vitt, F. (2016, September). A Reanalysis of MOPITT-CO observations. 2016 International Global Atmospheric Chemistry (IGAC) Project Science Conference.
• Kumar, R., Raman, A., Delle-Monache, L., Alessandrini, S., Chang, W., Gaubert, B., & Arellano, A. F. (2016, December). A novel method to improve MODIS AOD retrievals in cloudy pixels using an analog ensemble approach. AGU 2016 Fall Meeting.
• Montane, F., Fox, A. M., Arellano, A. F., Alexander, M. R., & Moore, D. J. (2016, Fall). A Model-Data Intercomparison of Carbon Fluxes, Pools, and LAI in the Community Land Model (CLM) and Alternative Carbon Allocation Schemes. American Geophysical Union.
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  Francesc Montane, Andrew M Fox, Avelino F Arellano, M Ross Alexander, David J Moore B21B-0444: A Model-Data Intercomparison of Carbon Fluxes, Pools, and LAI in the Community Land Model (CLM) and Alternative Carbon Allocation Schemes
• Tang, W., & Arellano, A. F. (2016, September). Investigating Combustion and Emission Trends in Megacities trhough Synthesis of Combustion Signatures Using Mulitple Datasets,. 2016 International Global Atmospheric Chemistry (IGAC) Project Science Conference.
• Arellano, A. F., Tang, W., & Deeter, M. (2015, December). Joint Analysis of Bulk Wildfire Characteristics from Multiple Satellite Retrievals. 2015 AGU Fall Meeting. San Francisco, CA: AGU.
• Barre, J., Edwards, D., Gaubert, B., Woren, H., Arellano, A. F., & Anderson, J. (2015, December). Carbon Monoxide Data Assimilation for Atmospheric Composition and Climate Science: Evaluating Performance with Current and Future Observations. 2015 AGU Fall Meeting. San Francisco, CA: AGU.
• Gaubert, B., Arellano, A. F., Barre, J., Worden, H., Emmons, L., Tilmes, S., Buchholz, R., Wiedinmyer, C., Vitt, F., & Anderson, J. (2015, December). Chemical Response of CESM/CAM-Chem to MOPITT CO Ensemble-based Chemical Data Assimilation. 2015 AGU Fall Meeting. San Francisco, CA: AGU.
• Mizzi, A., Arellano, A. F., Edwards, D., & Anderson, J. (2015, December). Comparison of the Assimilation of Compact Phase Space Retrievals (CPSRs) with Conventional Retrieval Assimilation Methods for MOPITT CO in WRF-Chem/DART. 2015 AGU Fall Meeting. San Francisco, CA: AGU.
• Montane, F., Fox, A., Arellano, A. F., Scaven, V., Alexander, M., & Moore, D. (2015, December). Comparing Different Model Structures for Carbon Allocation in the Community Land Model (CLM). 2015 AGU Fall Meeting. San Francisco, CA: AGU.
• Raman, A., Arellano, A. F., & Kumar, R. (2015, December). Using Combustion Tracers to Estimate Surface Black Carbon Distributions in WRF-Chem. 2015 AGU Fall Meeting. San Francisco, CA: AGU.
• Liu, Y., Matthes, J., Moore, D., Dietze, M., Arellano, A. F., Dawson, A., Fox, A., Goring, S., McLachlan, J., Montane, F., Moreno, G., Poulter, B., Quaife, T., Ricciuto, D., Schaefer, K., Steinkamp, S., Williams, J., & Team, P. (2014, December). Assessing the long-term performance of terrestrial ecosystem models in northeastern United States: linking model structure and output. 2014 AGU Fall Meeting. San Francisco, CA: AGU.
• Montane, F., Fox, A., Hoar, T., Arellano, A. F., Liu, Y., Moreno, G., Quife, T., Richardson, A., Trouet, V., Chen, M., Hollinger, D., & Moore, D. (2014, December). Assimilating Multiple Data Types in the Community Land Model (CLM) for Deciduous Forests in North America. 2014 AGU Fall Meeting. San Francisco, CA: AGU.
• Arellano, A. F. (2014, December). Constraints on Local-­to-­Regional Anthropogenic CO2 from Satellite Retrievals of Combustion-­related Trace Gases: Initial Assessment Using Observing System Simulation Experiments (OSSEs). 2014 AGU Fall Meeting. San Francisco, CA: AGU.
• Barre, J., Worden, H., Edwards, D., Arellano, A. F., & Lahoz, W. (2013, December). Monitoring lowermost tropospheric carbon monoxide from a geostationary constellation: observation simulations. 2013 AGU Fall Meeting. San Francisco, CA: AGU.
• Mizzi, A., Arellano, A. F., Edwards, D., & Anderson, J. (2015, January). Comparison of efficient algorithms for assimilating satellite partial column retrievals with WRF-Chem/DART. AMS 95th Annual Meeting. Phoenix, Arizona: AMS.
• Silva, S., Arellano, A. F., Yang, M., & Crosbie, E. (2013, December). Exploring the utility of satellite-based CO2-CO-NO2 sensitivities over urban regions and point sources as constraints on anthropogenic combustion. 2013 AGU Fall Meeting. San Francisco, CA: AGU.