Airborne passive microwave geophysical retrievals and applications in assessing environmental and aerosol impacts on maritime convection
Date of Award
Doctor of Philosophy (PhD)
Atmospheric and Earth Science
Susan van den Heever
Geophysical instruments, Radiometers, Atmosphere--Remote sensing, Convection (Meteorology)
Improvements to NASA’s Advanced Microwave Precipitation Radiometer (AMPR) have yielded physically realistic brightness temperatures (Tb) from the Olympic Mountains Experiment / Radar Definition Experiment (OLYMPEX/RADEX) and Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP2Ex). Multi-linear regression equations, developed to retrieve integrated cloud liquid water (CLW), water vapor (WV), and 10-m wind speed (WS), were tested using simulations, deconvolved AMPR Tb from OLYMPEX/RADEX, independent retrievals, and in situ data. Simulated retrievals yielded average CLW, WV, and WS root-mean-square deviations (RMSD) of 0.11 kg m-2, 1.28 kg m-2, and 1.11 m s-1, respectively, when compared with modeled atmospheric profiles, with median absolute deviations (MedAD) of 2.26 x 10-2 kg m-2, 0.22 kg m-2, and 0.55 m s-1. Applied to OLYMPEX/RADEX, the CLW, WV, and WS RMSD were 9.95 x 10-2 kg m-2, 2.00 kg m-2, and 2.35 m s-1, respectively, against independent retrievals, and MedAD were 2.88 x 10-2 kg m-2, 1.14 kg m-2, and 1.82 m s-1. Average WV (WS) MedAD against dropsondes were 1.95 kg m-2 (1.34 m s-1), further indicating strong retrieval performances. Expanding to CAMP2Ex involved retrieval improvements, validation, and science applications. CLW retrievals required modification for the maritime tropics, which yielded 1.94 x 10-2 kg m-2 RMSD against simulations. Validation against airborne Ku- and Ka-band radar-derived CLW produced high MedAD around 0.40 kg m-2; however, polarimeter-derived CLW offered MedAD around 8.08 x 10-2 kg m-2. AMPR CLW decreases within polarimeter-derived cloud-top height > 4 km may signify accretion and/or mixed-phase onset. Mean WV (WS) absolute deviation against 144 dropsondes was within target uncertainty at 8.27% (1.76 m s-1). Dropsonde-derived 0°C level height had moderate 0.49 (0.43) correlation with CLW (WS). Bulk correlations between nine dropsonde parameters and three convective metrics from AMPR and airborne radar across CAMP2Ex were relatively weak. Comparisons between five remote-sensing convective metrics and airborne-lidar-derived aerosol concentrations were performed within stratified CAMP2Ex environments in four sensitivity tests, wherein medium to relatively high aerosol concentrations were often directly correlated with convective intensity and frequency within favorable environments. Stratification using environmental lapse rates or K-Index generally yielded the highest correlations between convective metrics and aerosol concentrations.
Amiot, Corey G., "Airborne passive microwave geophysical retrievals and applications in assessing environmental and aerosol impacts on maritime convection" (2023). Dissertations. 278.