Dale M Ward
- Lecturer, Hydrology / Atmospheric Sciences
- Research Scientist, Atmospheric Physics
- 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
No activities entered.
Weather,Climate+SocietyATMO 336 (Fall 2021)
Weather,Climate+SocietyATMO 336 (Summer I 2021)
Weather,Climate+SocietyATMO 336 (Spring 2021)
Weather,Climate+SocietyATMO 336 (Fall 2020)
Weather,Climate+SocietyATMO 336 (Summer I 2020)
Intro Weather+ClimateATMO 170A1 (Spring 2020)
Weather,Climate+SocietyATMO 336 (Spring 2020)
Intro Weather+ClimateATMO 170A1 (Fall 2019)
Weather,Climate+SocietyATMO 336 (Fall 2019)
Weather,Climate+SocietyATMO 336 (Spring 2019)
Weather,Climate+SocietyATMO 336 (Fall 2018)
Weather,Climate+SocietyATMO 336 (Summer I 2018)
Weather,Climate+SocietyATMO 336 (Spring 2018)
Weather,Climate+SocietyATMO 336 (Fall 2017)
Independent StudyATMO 499 (Spring 2017)
Weather,Climate+SocietyATMO 336 (Spring 2017)
Weather,Climate+SocietyATMO 336 (Fall 2016)
Weather,Climate+SocietyATMO 336 (Spring 2016)
- 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.
- 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.More 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 GHz and 183 GHz water absorption lines. Our measurements of the 183 GHz line spectrum along an 820 m path revealed that the AM 6.2 spectroscopic model provdes a much better match to the observed spectrum than the MPM93 model. These comparisons also indicate that errors in the ATOMMS amplitude measurements are about 0.3%. Pressure sensitivity bodes well for ATOMMS as a climate instrument. Comparisons with a hygrometer revealed consistency at the 0.05 mb level, which is about 1% of the absolute humidity. Initial measurements of absorption by the 22 GHz line made along a 5.4 km path between two mountaintops captured a large increase in water vapor similar to that measured by several nearby hygrometers. A storm passage between the two instruments yielded our first measurements of extinction by rain and cloud droplets. Comparisons of ATOMMS 1.5 mm opacity measurements with measured visible opacity and backscatter from a weather radar revealed features simultaneously evident in all three datasets confirming the ATOMMS measurements. The combined ATOMMS, radar and visible information revealed the evolution of rain and cloud amounts along the signal path during the passage of the storm. The derived average cloud water content reached typical continental cloud amounts. These results demonstrated a significant portion of the information content of ATOMMS and its ability to penetrate through clouds and rain which is critical to its all-weather, climate monitoring capability. © 2012 Author(s).
- 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.
- 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.More infoAbstract: A new remote sensing concept extrapolated from the GPS occultation concept is presented in which the signal frequencies are chosen to determine atmospheric water, temperature, and the geopotential of atmospheric pressure surfaces. Using frequencies near the 22- and 183-GHz water lines allows not only the speed of light to be derived as a GPS occultation but also derivation of profiles of absorption caused by atmospheric water. Given the additional water information, moisture and temperature as well as the geopotential of pressure surfaces can be separated and solved for. Error covariance results indicate that the accuracies of individual water profiles will be 0.5%-3% extending from roughly 1-75-km altitude. Temperature accuracies of individual profiles will be sub-Kelvin from ∼1- to 70-km altitude depending on latitude and season. Accuracies of geopotential heights of pressure will be 10-20 m from the surface to 60-km altitude. These errors are random such that climatological averages derived from this data will be significantly more accurate. Owing to the limb-viewing geometry, the along-track resolution is comparable to the 200-300 km of the GPS occultation observations, but the shorter 22- and 183-GHz wavelengths improve the diffraction-limited vertical resolution to 100-300 m. The technique can be also used to determine profiles of other atmospheric constituents such as upper-tropospheric and stratospheric ozone by using frequencies near strong lines of that constituent. The combined dynamic range, accuracy, vertical resolution, and ability to penetrate clouds far surpass that of any present or planned satellite sensors. A constellation of such sensors would provide an all-weather, global remote sensing capability including full sampling of the diurnal cycle for process studies related to water, climate research, and weather prediction in general.
- 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.More infoAbstract: Present Global Positioning System Meteorology (GPS/MET) refractivity profiles cannot distinguish between refractivity effects due to water vapor and those due to air density. Current methods of resolving the ambiguity rely heavily on ancillary upper-air data, such as National Centers for Environmental Prediction and European Centre for Medium-Range Weather Forecasts (ECMWF) analyses. However, the accuracy of these ancillary sources suffers in regions where upper-air data are sparse. A method of separating the water vapor and temperature effects in GPS/MET-derived refractivity profiles with the addition of only ancillary surface pressure and temperature data and the hydrostatic assumption is discussed. Water vapor and temperature data derived from this method are presented and compared with accepted values. This method allows for the construction of temperature profiles with a mean bias of 0.33 K and a mean standard deviation of 1.86 K when compared with ECMWF data from 30 to 1000 mb. Height fields can also be corrected to within an average bias of 6 m and a standard deviation of 31 m. These corrected profiles result in retrieved water vapor pressure profiles with an average bias of 0.19 mb and a standard deviation of 0.53 mb.
- 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.More infoAbstract: Climate simulations of the National Center for Atmospheric Research (NCAR) community climate model version 2 (CCM2) are compared with several data sets. These data sets are a multiyear climatology of the Earth Radiation Budget Experiment (ERBE) top-of-the-atmosphere (TOA) radiative fluxes, the International Satellite Cloud Climatology Prolject (ISCCP) cloudiness, and the Surface Radiation Budget (SRB) Project surface insolation. The comparison focuses on global and regional spatial scales and the seasonal timescale. A revised computational scheme of the cloud optical properites is introduced in the solar and longwave radiative transfer parameterizations of CCM2. -from Authors
- 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.More infoAbstract: A comparison of the monthly mean shortwave surface radiation budget (SRB) obtained from the World Climate Research Program (WCRP) shortwave global dataset with that simulated by the National Center for Atmopsheric Research Community Climate Model version 2.0 (CCM2) is presented. WCRP/SRB data are derived from the International Satellite Cloud Climatology Project (ISCCP) C1 data using the Pinker algorithm. The largest discrepancies are found in the summer midlatitude regions where CCM2 overestimates surface solar fluxes relative to Pinker by as much as 100 W m-2. Most of the differences are associated with deficiencies in CCM2's prediction of cloud optical properties and cloud amount.
- Kursinski, E. R., & Ward, D. M. (2015, December). Atmospheric Profiling Combining the Features of GPS RO & MLS. AGU Fall Meeting. San Francisco, CA: AGU.