Dale M Ward
- Lecturer, Hydrology / Atmospheric Sciences
- Research Scientist, Atmospheric Physics
- Member of the Graduate Faculty
Contact
- (520) 626-7261
- John W. Harshbarger Building, Rm. 216
- Tucson, AZ 85721
- dward@arizona.edu
Degrees
- Ph.D. Atmospheric Science
- University of Arizona, Tucson, Arizona, United States
- Atmospheric Sounding from Satellite Solar Occultation Refraction Measurements
- M.S. Atmospheric Science
- University of Arizona, Tucson, Arizona, United States
- Comparison of the Surface Solar Radiation Budget Derived from Satellite Data with that Simulated by the NCAR CCM2
- B.S. Electrical Engineering
- Case Western Reserve University, Cleveland, Ohio, United States
Interests
No activities entered.
Courses
2024-25 Courses
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Physical Meteorology I
ATMO 451A (Fall 2024) -
Physical Meteorology I
ATMO 551A (Fall 2024)
2023-24 Courses
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Fndmtls of Atmo Sciences
ATMO 436A (Spring 2024) -
Fndmtls of Atmo Sciences
ATMO 536A (Spring 2024) -
Intro Weather+Climate
ATMO 170A1 (Fall 2023) -
Weather,Climate+Society
ATMO 336 (Fall 2023)
2022-23 Courses
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Weather,Climate+Society
ATMO 336 (Summer I 2023) -
Intro Weather+Climate
ATMO 170A1 (Spring 2023) -
Weather,Climate+Society
ATMO 336 (Spring 2023) -
Weather,Climate+Society
ATMO 336 (Fall 2022)
2021-22 Courses
-
Weather,Climate+Society
ATMO 336 (Summer I 2022) -
Intro Weather+Climate
ATMO 170A1 (Spring 2022) -
Weather,Climate+Society
ATMO 336 (Spring 2022) -
Weather,Climate+Society
ATMO 336 (Fall 2021)
2020-21 Courses
-
Weather,Climate+Society
ATMO 336 (Summer I 2021) -
Weather,Climate+Society
ATMO 336 (Spring 2021) -
Weather,Climate+Society
ATMO 336 (Fall 2020)
2019-20 Courses
-
Weather,Climate+Society
ATMO 336 (Summer I 2020) -
Intro Weather+Climate
ATMO 170A1 (Spring 2020) -
Weather,Climate+Society
ATMO 336 (Spring 2020) -
Intro Weather+Climate
ATMO 170A1 (Fall 2019) -
Weather,Climate+Society
ATMO 336 (Fall 2019)
2018-19 Courses
-
Weather,Climate+Society
ATMO 336 (Spring 2019) -
Weather,Climate+Society
ATMO 336 (Fall 2018)
2017-18 Courses
-
Weather,Climate+Society
ATMO 336 (Summer I 2018) -
Weather,Climate+Society
ATMO 336 (Spring 2018) -
Weather,Climate+Society
ATMO 336 (Fall 2017)
2016-17 Courses
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Independent Study
ATMO 499 (Spring 2017) -
Weather,Climate+Society
ATMO 336 (Spring 2017) -
Weather,Climate+Society
ATMO 336 (Fall 2016)
2015-16 Courses
-
Weather,Climate+Society
ATMO 336 (Spring 2016)
Scholarly Contributions
Books
- Kursinski, E. R., Ward, D., Otarola, A., Frehlich, R., Groppi, C., Albanna, S., Shein, M., Bertiger, W., Pickett, H., & Ross, M. (2009). The active temperature, ozone and moisture microwave spectrometer (ATOMMS).
Chapters
- Kursinski, E. R., Ward, D. M., Otarola, A., Frehlich, R., Groppi, C., Albanna, S., Shein, M., Bertiger, W., Pickett, H., Ross, M., & Bertiger, W. I. (2009). The Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). In New Horizons in Atmospheric Research(pp 295 - 313). Springer, Berlin, Heidelberg. doi:10.1007/978-3-642-00321-9_24More infoThe Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS) is designed to observe Earth’s climate. It extends and overcomes several limitations of the GPS radio occultation capabilities by simultaneously measuring atmospheric bending and absorption at frequencies approximately 10 and 100 times higher than GPS. This paper summarizes several important conceptual improvements to ATOMMS made since OPAC-1 including deriving the hydrostatic upper boundary condition directly from the ATOMMS observations, our much improved understanding of the impact of turbulence and its mitigation, and a new approach to deriving atmospheric profiles in the presence of inhomogeneous liquid water clouds. ATOMMS performance significantly exceeds that of radiometric sounders in terms of precision and vertical resolution and degrades only slightly in the presence of clouds and it does so independently of models. Our aircraft-to-aircraft occultation demonstration of ATOMMS performance will begin in 2009 representing a major step towards an orbiting observing system.
- Herman, B. M., Feng, D., Flittner, D. E., Kursinski, E. R., Syndergaard, S., & Ward, D. M. (2004). An overview of the University of Arizona ATOMS project. In Occultations for Probing Atmosphere and Climate(pp 189-200). Springer Berlin Heidelberg. doi:10.1007/978-3-662-09041-1_18More infoResults from the now well known GPS/MET experiment have demonstrated the capabilities of radio occultation techniques for remotely sensing certain atmospheric properties (Ware et al. 1996; Rocken et al. 1997; Kursinski et al. 1997). The GPS/MET experiment was designed to provide vertical atmospheric profiles of temperature, pressure, density, and geopotential height from determinations of the vertical refractivity profiles. Indeed, for altitudes from a few km above the surface to about 40 km, extremely accurate profiles were obtained with very good vertical resolution. At altitudes below about 5–8 km, an ambiguity may exist however, when using just the GPS frequencies, due to the presence of water vapor. Water vapor, as well as dry air, affects the refractivity of the atmosphere, and the two variables cannot be separated without additional assumptions, or additional information. In polar regions where water vapor amounts are generally quite low, accurate temperatures can usually be retrieved by assuming the water vapor to be zero. In tropical regions, where low tropospheric temperature profiles are quite constant from day to day, water vapor profiles may be recovered from the refractivity profiles by assuming the temperature profile is known. It is in mid-latitudes where this ambiguity is most important. Techniques have been developed to overcome some of this difficulty, but uncertainties still exist in the recovered water vapor profiles, especially in data sparse regions. The ATOMS (Active Tropospheric Ozone and Moisture Sounder) project was conceived in order to provide a totally independent measurement to use for water vapor retrievals. A preliminary study indicated that the use of phase measurements as in the GPS/MET experiment, but near a water vapor absorption line where the refractivity undergoes a rapid variation, would not provide the necessary sensitivity due to the small mixing ratio of water vapor. However amplitude measurements at various frequencies within and near the line would provide a method to retrieve vertical water vapor profiles. In this paper we report on the progress we have made to date in developing this technique. By using various frequencies within both the 22 GHz and 183 GHz water vapor absorption lines, it will be shown that usable profiles may be recovered over a wide range of altitudes. A similar study will be presented using the 195 GHz ozone absorption line to recover ozone profiles from the mid-troposphere to well up into the stratosphere.
- Kursinski, E. R., Feng, D., Flittner, D. E., Hajj, G. A., Herman, B. M., Romberg, F., Syndergaard, S., Ward, D. M., & Yunck, T. P. (2004). An Active Microwave Limb Sounder for Profiling Water Vapor, Ozone, Temperature, Geopotential, Clouds, Isotopes and Stratospheric Winds. In Occultations for Probing Atmosphere and Climate(pp 173 - 187). Springer, Berlin, Heidelberg. doi:10.1007/978-3-662-09041-1_17More infoWe summarize our findings on the performance of a radio occultation system operating at cm and mm wavelengths selected to profile atmospheric water, ozone and other constituents such as water isotopes as well as temperature, the geopotential of atmospheric pressure surfaces and clouds. Furthermore winds in the upper stratosphere can be determined from the Doppler shift of the line center. Our analysis indicates that such a system will yield dramatically higher vertical resolution, precision and accuracy than present and planned passive radiometric systems.
- Syndergaard, S., Flittner, D. E., Kursinski, E. R., Feng, D., Herman, B. M., Ward, D. M., & Herman, B. M. (2004). Simulating the Influence of Horizontal Gradients on Retrieved Profiles from ATOMS Occultation Measurements — a Promising Approach for Data Assimilation. In Occultations for Probing Atmosphere and Climate(pp 221 - 232). Springer Berlin Heidelberg. doi:10.1007/978-3-662-09041-1_20More infoThe Active Tropospheric Ozone and Moisture Sounder (ATOMS) is envisaged to provide information about the vertical distribution of atmospheric refractivity, volume absorption coefficients, temperature, pressure, water vapor pressure, clouds, and ozone via observations of the phase and amplitudes of LEO—LEO occultation signals at certain frequencies. The retrieval of these products assumes that the atmosphere in the vicinity of the ray path tangent points are spherically symmetrical. Since the tropospheric horizontal distribution of water vapor can be quite variable over relatively short distances, this assumption is far from perfect and may result in very large errors in retrieved profiles of volume absorption coefficients and water vapor pressure (not considering clouds). We assess close to worst-case errors in retrieved profiles of refractivity and volume absorption coefficients — from which temperature and water vapor pressure can be derived — by simulating the occultation measurements in cases where the signals propagate through a model of a weather front, including moisture. If the retrieved profiles are compared to the corresponding model profiles following the loci of the ray path tangent points, fractional errors in volume absorption coefficients can exceed 70%. An alternative comparison involves a linear mapping of the two-dimensional structure in the occultation plane into a one-dimensional profile, mimicking the occultation geometry as well as the subsequent data inversion process. The maximum fractional errors in volume absorption coefficients, comparing the retrieved profiles against such mapped profiles, are about 10%. Corresponding fractional errors in refractivity are about 10 times smaller. The linear mapping approach is simple and fast, and seems to be a good candidate as an observation operator for future data assimilation of occultation measurements.
Journals/Publications
- Wu, P., Dong, X., Xi, B., Ward, D. M., & Tian, J. (2020). Profiles of MBL Cloud and Drizzle Microphysical Properties Retrieved From Ground-Based Observations and Validated by Aircraft In Situ Measurements Over the Azores. JGR Atmospheres, 125(8). doi:https://doi.org/10.1029/2019JD032205More infoAbstract: The profiles of marine boundary layer (MBL) cloud and drizzle microphysical properties are important for studying the cloud-to-rain conversion and growth processes in MBL clouds. However, it is challenging to simultaneously retrieve both cloud and drizzle microphysical properties within an MBL cloud layer using ground-based observations. In this study, methods were developed to first decompose drizzle and cloud reflectivity in MBL clouds from Atmospheric Radiation Measurement cloud radar reflectivity measurements and then simultaneously retrieve cloud and drizzle microphysical properties during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) campaign. These retrieved microphysical properties, such as cloud and drizzle particle size (rc and rm,d), their number concentration (Nc and Nd) and liquid water content (LWCc and LWCd), have been validated by aircraft in situ measurements during ACE-ENA (~158 hr of aircraft data). The mean surface retrieved (in situ measured) rc, Nc, and LWCc are 10.9 μm (11.8 μm), 70 cm−3 (60 cm−3), and 0.21 g m−3 (0.22 g m−3), respectively. For drizzle microphysical properties, the retrieved (in situ measured) rd, Nd, and LWCd are 44.9 μm (45.1 μm), 0.07 cm−3 (0.08 cm−3), and 0.052 g m−3 (0.066 g m−3), respectively. Treating the aircraft in situ measurements as truth, the estimated median retrieval errors are ~15% for rc, ~35% for Nc, ~30% for LWCc and rd, and ~50% for Nd and LWCd. The findings from this study will provide insightful information for improving our understanding of warm rain processes, as well as for improving model simulations. More studies are required over other climatic regions.
- Zheng, X., Dong, X., Ward, D. M., Xi, B., Wu, P., & Wang, Y. (2022). Aerosol-Cloud-Precipitation Interactions in a typical Overcast Close-cellular and Non-homogenous MBL Stratocumulus Cloud. Advances in Atmospheric Sciences..
- Zheng, X., Dong, X., Ward, D. M., Xi, B., Wu, P., & Wang, Y. (2022). Aerosol-Cloud-Precipitation Interactions in a Closed-cell and Non-homogenous MBL Stratocumulus Cloud. Advances in Atmospheric Sciences, 39(12), 2107-2123.
- Wu, P., Dong, X., Xi, B., Tian, J., & Ward, D. M. (2020). Profiles of MBL Cloud and Drizzle Microphysical Properties Retrieved From Ground-Based Observations and Validated by Aircraft In Situ Measurements Over the Azores. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 125(9).
- Wu, P., Dong, X., Xi, B., Tian, J., & Ward, D. M. (2020). Profiles of MBL Cloud and Drizzle Microphysical Properties Retrieved From Ground-Based Observations and Validated by Aircraft In Situ Measurements Over the Azores. Journal of Geophysical Research: Atmospheres, 125(9).
- Ward, D. M., Kursinski, E. R., Otarola, A. C., Stovern, M., McGhee, J., Young, A., Hainsworth, J., Hagen, J., Sisk, W., & Reed, H. (2019). Retrieval of water vapor using ground-based observations from a prototype ATOMMS active centimeter- and millimeter-wavelength occultation instrument. ATMOSPHERIC MEASUREMENT TECHNIQUES, 12(3), 1955-1977.
- Ward, D. M., Robert Kursinski, E., Otarola, A. C., Stovern, M., McGhee, J., Young, A., Hainsworth, J., Hagen, J., Sisk, W., & Reed, H. (2019). Retrieval of water vapor using ground-based observations from a prototype ATOMMS active centimeter- and millimeter-wavelength occultation instrument. Atmospheric Measurement Techniques, 12(3), 1955-1977.
- Ward, D., Young, A., Ward, D. M., Stovern, M., Sisk, W., Reed, H., Otarola, A., Mcgee, J., Kursinski, E. R., Hainsworth, J., & Hagen, J. (2019). Retrieval of Water Vapor using Ground-based Observations from a Prototype ATOMMS Active cm- and mm- Wavelength Occultation Instrument. Atmospheric Measurement Techniques Discussions, 12(3), 1955-1977. doi:https://doi.org/10.5194/amt-12-1955-2019More infoAbstract. A fundamental goal of satellite weather and climate observations is profiling the atmosphere with in situ-like precision and resolution with absolute accuracy and unbiased, all-weather, global coverage. While GPS radio occultation (RO) has perhaps come closest in terms of profiling the gas state from orbit, it does not provide sufficient information to simultaneously profile water vapor and temperature. We have been developing the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS) RO system that probes the 22 and 183 GHz water vapor absorption lines to simultaneously profile temperature and water vapor from the lower troposphere to the mesopause. Using an ATOMMS instrument prototype between two mountaintops, we have demonstrated its ability to penetrate through water vapor, clouds and rain up to optical depths of 17 (7 orders of magnitude reduction in signal power) and still isolate the vapor absorption line spectrum to retrieve water vapor with a random uncertainty of less than 1 %. This demonstration represents a key step toward an orbiting ATOMMS system for weather, climate and constraining processes. ATOMMS water vapor retrievals from orbit will not be biased by climatological or first-guess constraints and will be capable of capturing nearly the full range of variability through the atmosphere and around the globe, in both clear and cloudy conditions, and will therefore greatly improve our understanding and analysis of water vapor. This information can be used to improve weather and climate models through constraints on and refinement of processes affecting and affected by water vapor.
- Calbet, X., Peinado-Galan, N. .., Desouza-Machado, S. .., Robert Kursinski, E., Oria, P., Ward, D., Otarola, A., R??podas, P., & Kivi, R. (2018). Can turbulence within the field of view cause significant biases in radiative transfer modeling at the 183 GHz band?. Atmospheric Measurement Techniques, 11(12), 6409-6417.
- Calbet, X., Peinado-Galan, N., DeSouza-Machado, S., Kursinski, E. R., Oria, P., Ward, D., Otarola, A., Ripodas, P., & Kivi, R. (2018). Can turbulence within the field of view cause significant biases in radiative transfer modeling at the 183 GHz band?. ATMOSPHERIC MEASUREMENT TECHNIQUES, 11(12), 6409-6417.
- Kursinski, E. R., Ward, D., Otarola, A. C., McGhee, J., Stovern, M., Sammler, K., Reed, H., Erickson, D., McCormick, C., & Griggs, E. (2016). Atmospheric profiling via satellite to satellite occultations near water and ozone absorption lines for weather and climate. EARTH OBSERVING MISSIONS AND SENSORS: DEVELOPMENT, IMPLEMENTATION, AND CHARACTERIZATION IV, 9881.
- Kursinski, E. R., Ward, D., Stovern, M., Otarola, A. C., Young, A., Wheelwright, B., Stickney, R., Albanna, S., Duffy, B., Groppi, C., & Hainsworth, J. (2012). Development and testing of the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS) cm and mm wavelength occultation instrument. ATMOSPHERIC MEASUREMENT TECHNIQUES, 5(2), 439-456.More infoWe present initial results from testing a new remote sensing system called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). ATOMMS is designed as a satellite-to-satellite occultation system for monitoring climate. We are developing the prototype instrument for an aircraft to aircraft occultation demonstration. Here we focus on field testing of the ATOMMS instrument, in particular the remote sensing of water by measuring the attenuation caused by the 22 GHz and 183 GHz water absorption lines.
- Kursinski, E. R., Ward, D., Stovern, M., Otarola, A. C., Young, A., Wheelwright, B., Stickney, R., Albanna, S., Duffy, B., Groppi, C., & Hainsworth, J. (2012). Development and testing of the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS) cm and mm wavelength occultation instrument. Atmospheric Measurement Techniques, 5(2), 439-456.
- Young, A., Wheelwright, B., Ward, D., Stovern, M., Stickney, R., Otarola, A. C., Kursinski, E. R., Hainsworth, J., Groppi, C., Duffy, B., & Albanna, S. (2011). Development and testing of the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS) cm and mm wavelength occultation instrument. Atmospheric Measurement Techniques Discussions, 4(4), 4667-4715. doi:10.5194/amtd-4-4667-2011More infoAbstract. We present initial results from testing a new remote sensing system called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). ATOMMS is designed as a satellite to satellite occultation system for monitoring climate. We are developing the prototype instrument for an aircraft to aircraft occultation demonstration. Here we focus on field testing of the ATOMMS instrument, in particular the remote sensing of water by measuring the attenuation caused by the 22 and 183 GHz water absorption lines. The 183 GHz line spectrum was measured along an 820 m path and compared with two spectroscopic models. This revealed that the AM 6.2 model is a much better match to the observed spectrum than the MPM93 model. These comparisons also indicate the ATOMMS amplitude errors were at the 0.3 % level. Comparisons with a hygrometer showed tracking consistent at the 0.05 mb level which is about 1 % of the absolute humidity. Initial 22 GHz measurements along a 5.4 path between two mountaintops showed the 22 GHz channels tracking a large change in water vapor. Ground truth is much harder to establish.
- Kursinski, E. R., Otarola, A., Ward, D., Young, A., Albanna, S., Groppi, C., Stickney, R., Stovern, M., Wheelwright, B., Duffy, B., Schein, M., Sammler, K., Frehlich, R., Bertiger, W., Pickett, H., Rind, D., & Ross, M. (2010). The Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS), A new global climate sensor. International Geoscience and Remote Sensing Symposium (IGARSS), 2952-2955.More infoAbstract: We are developing a new remote sensing system at the University of Arizona called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). ATOMMS combines many of the best features of GPS Radio Occultation (RO) and the Microwave Limb Sounder (MLS) by actively probing cm to sub-mm wavelength atmospheric absorption features via satellite-to-satellite occultation. ATOMMS will provide an unprecedented combination of features for monitoring climate from orbit. With funding from NSF and aircraft time from NASA, we will demonstrate the ATOMMS concept via high altitude aircraft-to-aircraft occultations in 2011. Here we summarize the ATOMMS concept and demonstration project and provide early test results from the instrument indicative of ATOMMS capabilities and performance. © 2010 IEEE.
- Kursinski, E. R., Young, A., Otarola, A., Stovern, M., Wheelwright, B., Ward, D., Sammler, K., Stickney, R., Groppi, C., Banna, S. A., Schein, M., Bell, S., Bertiger, W., Miller, M., & Pickett, H. (2010). Laboratory and ground testing results from ATOMMS: The active temperature, ozone and moisture microwave spectrometer. 21st International Symposium on Space Terahertz Technology 2010, ISSTT 2010, 155-163.More infoAbstract: Abstract- ATOMMS represents a new class of active, airborne, limb-viewing spectrometer that is a cross between Global Positioning System (GPS) occultations and NASA's Microwave Limb Sounder. ATOMMS will characterize atmospheric water vapour and ozone by actively probing the absorption lines at 22.2 GHz, 183.3 GHz and 195 GHz, respectively. Two instrument packages are being constructed for NASA's WB-57F high altitude research aircraft, now equipped with precise WAVES gimballed pointing systems. One aircraft will generate multiple tones near the 22 GHz water line and 183 GHz to 204 GHz absorption lines and transmit them across the Earth's limb through the atmosphere to receivers on a second aircraft. Flight paths of the two aircraft begin over the horizon, with the two aircraft flying at 65 kft altitude. This creates a rising occultation geometry as the aircrafts fly towards each other. ATOMMS provides the sensitivity, vertical spatial resolution and accuracy needed to satisfy key monitoring needs for temperature, pressure, moisture and ozone. The 100 to 200 m ATOMMS vertical resolution will far surpass the 1 to 4 km vertical resolution of present state-of-the-art satellite radiometers opening a window into atmospheric scales previously inaccessible from space. Predicted precisions of individual ATOMMS temperature, pressure and moisture profiles are unprecedented at ~0.4 K, 0.1% and 1-3% respectively, extending from near the surface to the flight altitude of ~20 km. ATOMMS ozone profiles precise to 1-3% will extend from the upper troposphere well into the mesosphere. Other trace constituents such as water isotopes can be measured with performance similar to that of ozone. The ATOMMS experiment is a pathfinder experiment for eventual implementation on a constellation of satellites. Space observations from multiple satellites in precessing orbits will allow for global spatial coverage and increased altitude coverage. Our long term goal is a constellation of approximately a dozen small spacecraft making ATOMMS measurements that will provide dense, global coverage and complete cloudpenetration and diurnal sampling every orbit. The ATOMMS instruments have been completed and are now undergoing extensive laboratory and ground testing. We report on the laboratory testing results including the differential amplitude and phase stability of the instrument and systems integration testing. We will also report on ground testing experiments, where the ATOMMS instruments, located on two building tops, were used to measure atmospheric water vapour content. Comparison measurements were made using in-situ hygrometers. Further ground-based tests are planned to exercise the full ATOMMS system, including the GPS-based positioning and time correction system, accelerometer system and dual-one-way phase correction system. We will also discuss planned instrument upgrades to be implemented in preparation for air-to-ground and air-to-air flights on the WB-57F aircraft.
- Kursinski, E. R., Ward, D., Otarola, A., Frehlich, R., Groppi, C., Albanna, S., Shein, M., Bertiger, W., Pickett, H., & Ross, M. (2009). The active temperature, ozone and moisture microwave spectrometer (ATOMMS). New Horizons in Occultation Research: Studies in Atmosphere and Climate, 295-313.More infoAbstract: The Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS) is designed to observe Earth's climate. It extends and overcomes several limitations of the GPS radio occultation capabilities by simultaneously measuring atmospheric bending and absorption at frequencies approximately 10 and 100 times higher than GPS. This paper summarizes several important conceptual improvements to ATOMMS made since OPAC-1 including deriving the hydrostatic upper boundary condition directly from the ATOMMS observations, our much improved understanding of the impact of turbulence and its mitigation, and a new approach to deriving atmospheric profiles in the presence of inhomogeneous liquid water clouds. ATOMMS performance significantly exceeds that of radiometric sounders in terms of precision and vertical resolution and degrades only slightly in the presence of clouds and it does so independently of models. Our aircraft-to-aircraft occultation demonstration of ATOMMS performance will begin in 2009 representing a major step towards an orbiting observing system. © 2009 Springer-Verlag Berlin Heidelberg.
- Matichuk, R., Barbaris, B., Betterton, E. A., Hori, M., Murao, N., Ohta, S., & Ward, D. (2006). A decade of aerosol and gas precursor chemical characterization at Mt. Lemmon, Arizona (1992 to 2002). Journal of the Meteorological Society of Japan, 84(4), 653-670.
- Kursinski, E. R., Syndergaard, S., Flittner, D., Feng, D., Hajj, G., Herman, B., Ward, D., & Yunck, T. (2002). A microwave occultation observing system optimized to characterize atmospheric water, temperature, and geopotential via absorption. Journal of Atmospheric and Oceanic Technology, 19(12), 1897-1914.
- Ward, D. M. (2002). A semisimultaneous inversion algorithm for SAGE III. Journal of Geophysical Research Atmospheres, 107(24).
- Ward, D. M. (2002). A semisimultaneous inversion algorithm for SAGE III. Journal of Geophysical Research D: Atmospheres, 107(24).More infoAbstract: The Stratospheric Aerosol and Gas Experiment (SAGE) III instrument was successfully launched into orbit on 10 December 2001. The planned operational species separation inversion algorithm will utilize a stepwise retrieval strategy. This paper presents an alternative, semisimultaneous species separation inversion that simultaneously retrieves all species over user-specified vertical intervals or blocks. By overlapping these vertical blocks, retrieved species profiles over the entire vertical range of the measurements are obtained. The semisimultaneous retrieval approach provides a more straightforward method for evaluating the error coupling that occurs among the retrieved profiles due to various types of input uncertainty. Simulation results are presented to show how the semisimultaneous inversion can enhance understanding of the SAGE III retrieval process. In the future, the semisimultaneous inversion algorithm will be used to help evaluate the results and performance of the operational inversion. Compared to SAGE II, SAGE III will provide expanded and more precise spectral measurements. This alone is shown to significantly reduce the uncertainties in the retrieved ozone, nitrogen dioxide, and aerosol extinction profiles for SAGE III. Additionally, the well-documented concern that SAGE II retrievals are biased by the level of volcanic aerosol is greatly alleviated for SAGE III. Copyright 2002 by the American Geophysical Union.
- O'Sullivan, D., Herman, B. M., Feng, D., Flittner, D. E., & Ward, D. M. (2000). Retrieval of water vapor profiles from GPS/MET radio occultations. Bulletin of the American Meteorological Society, 81(5), 1031-1040.
- Ward, D. M., & Herman, B. M. (1998). Refractive sounding by use of satellite solar occultation measurements including an assessment of its usefulness to the Stratospheric Aerosol and Gas Experiment Program. Applied Optics, 37(36), 8306-8317.More infoPMID: 18301653;Abstract: Vertical profiles of atmospheric density and temperature obtained with the technique of solar refractive sounding can potentially be used to improve satellite solar occultation trace species retrievals by reducing the uncertainties associated with Rayleigh scattering and the temperature dependence of absorption bands. The required refraction measurements and the algorithm utilized to recover density and temperature are described. Simulations are performed to estimate the measurement accuracy that is necessary to retrieve useful meteorological soundings at stratospheric altitudes. The method is applied to data measured by the Stratospheric Aerosol and Gas Experiment (SAGE) II. Unfortunately, because of poor vertical sampling and measurement uncertainties, the meteorological profiles derived from the SAGE II data are not consistently accurate enough to improve the SAGE II estimates for the concentrations of trace species. However, the qualitatively decent results provide optimism for future development and implementation of visible refractive sounding as a tool to help improve the accuracy of trace species retrievals within solar or stellar occultation experiments, including the SAGE III program. © 1998 Optical Society of America.
- Hahmann, A. N., Ward, D. M., & Dickinson, R. E. (1995). Land surface temperature and radiative fluxes response of the NCAR CCM2/biosphere-atmosphere transfer scheme to modifications in the optical properties of clouds. Journal of Geophysical Research, 100(D11), 23,239-23,252.
- Ward, D. M. (1995). Comparison of the surface solar radiation budget derived from satellite data with that simulated by the NCAR CCM2. Journal of Climate, 8(11), 2824-2842.
Proceedings Publications
- Xi, B., Wu, P., Ward, D. M., Tian, J., & Dong, X. (2019, December). Retrieving marine boundary layer cloud and drizzle microphysical properties using ground-based and aircraft in situ measurements during ACE-ENA. In AGU, fall 2019.
- Zheng, X., Xi, B., Wu, P., Ward, D. M., & Dong, X. (2019, December). Impacts of aerosols on MBL Cloud Microphysical and Drizzle Properties using Aircraft in-Situ Measurements during ACE-ENA. In AGU, Fall 2019.More infoAbstract: The relationships of marine stratocumulus microphysical properties, drizzle properties, and aerosol properties are examined using in-situ measurements obtained from the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA). During Summer 2017 and Winter 2018, 6 research flights and 5 research flights are selected as drizzling and non-drizzling cloud cases respectively, in order to investigate the cloud and drizzle susceptibilities to aerosol. The aerosol first indirect effect is well manifested in aircraft measurements. The cloud droplet number concentrations (Nd) show increasing trends with sub-cloud aerosol loading for both drizzle and non-drizzle cases. While the cloud droplet effective radius (re) decrease with increasing aerosol loading for non-drizzle cases. As for drizzle cases, re values show no significant dependence on the aerosol, which might due to the substantial impact of drizzle formation process on the droplet size distributions. It is noteworthy that there are different aerosol-cloud interactions near cloud-top and cloud-base regions, partly owing to the different air masses above (advected from polluted regions) and below (local source) the cloud layer. In terms of cloud drizzle susceptibility, relatively lower leg-mean cloud-base drizzle rates are found accompanied by relatively higher sub-cloud aerosol number concentrations, indicating increasing aerosol loading does effectively reduce drizzle production. Under given liquid water content condition, the drizzle susceptibility of Winter cloud cases is slightly higher than Summer cloud cases, suggesting the meteorological factors and aerosol sources might be jointly contributing to the aerosol suppression effect on drizzle.
- Kursinski, E. R., Ward, D., Otarola, A. C., McGhee, J., Stovern, M., Sammler, K., Reed, H., Erickson, D., McCormick, C., & Griggs, E. (2016). Atmospheric profiling via satellite to satellite occultations near water and ozone absorption lines for weather and climate.
- Kursinski, E. R., Otarola, A., Ward, D., Young, A., Albanna, S., Groppi, C., Stickney, R., Stovern, M., Wheelwright, B., Duffy, B., Schein, M., Sammler, K., Frehlich, R., Bertiger, W., Pickett, H., Rind, D., & Ross, M. (2010). The Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS), A new global climate sensor.
- Robert Kursinski, E., Young, A., Otarola, A., Stovern, M., Wheelwright, B., Ward, D., Sammler, K., Stickney, R., Groppi, C., Banna, S. A., Schein, M., Bell, S., Bertiger, W., Miller, M., & Pickett, H. (2010). Laboratory and ground testing results from ATOMMS: The active temperature, ozone and moisture microwave spectrometer.
Poster Presentations
- Kursinski, E. R., & Ward, D. M. (2015, December). Atmospheric Profiling Combining the Features of GPS RO & MLS. AGU Fall Meeting. San Francisco, CA: AGU.