Dual-Polarization Deconvolution and Geophysical Retrievals from the Advanced Microwave Precipitation Radiometer during OLYMPEX/RADEX

Abstract

AbstractRecent upgrades, calibration, and scan-angle bias reductions to the Advanced Microwave Precipitation Radiometer (AMPR) have yielded physically realistic brightness temperatures (Tb) from the Olympic Mountains Experiment and Radar Definition Experiment (OLYMPEX/RADEX) dataset. Measured mixed-polarization Tb were converted to horizontally and vertically polarized Tb via dual-polarization deconvolution, and linear regression equations were developed to retrieve integrated cloud liquid water (CLW), water vapor (WV), and 10-m wind speed (WS) using simulated AMPR Tb and modeled atmospheric profiles. These equations were tested using AMPR Tb collected during four OLYMPEX/RADEX cases; the resulting geophysical values were compared with independent retrieval (1DVAR) results from the same dataset, while WV and WS were also compared with in situ data. Geophysical calculations using simulated Tb yielded relatively low retrieval and crosstalk errors when compared with modeled profiles; average CLW, WV, and WS root-mean-square deviations (RMSD) were 0.11 mm, 1.28 mm, and 1.11 m s−1, respectively, with median absolute deviations (MedAD) of 2.26 × 10−2 mm, 0.22 mm, and 0.55 m s−1, respectively. When applied to OLYMPEX/RADEX data, the new retrieval equations compared well with 1DVAR; CLW, WV, and WS RMSD were 9.95 × 10−2 mm, 2.00 mm, and 2.35 m s−1, respectively, and MedAD were 2.88 × 10−2 mm, 1.14 mm, and 1.82 m s−1, respectively. WV MedAD between the new equations and dropsondes were 2.10 and 1.80 mm at the time and location of minimum dropsonde altitude, respectively, while WS MedAD were 1.15 and 1.53 m s−1, respectively, further indicating the utility of these equations.