Hurricane Warm‐Core Retrievals from AMSU‐A and Remapped ATMS Measurements with Rain Contamination Eliminated

Abstract

AbstractDue to a shorter effective integration time for each field of view of the Advanced Microwave Temperature Sounder (ATMS) onboard the Suomi National Polar‐orbiting Partnership (S‐NPP) satellite than that for the Advanced Microwave Sounding Unit‐A (AMSU‐A) onboard previous National Oceanic and Atmospheric Administration (NOAA) polar‐orbiting satellites NOAA‐15 to NOAA‐19, ATMS temperature‐sounding channels have higher observational resolutions and larger noise equivalent differential temperatures than the corresponding AMSU‐A channels. The high resolution of the ATMS allows hurricane rainband features that are not resolvable by AMSU‐A to be captured. But the larger noise equivalent differential temperature of ATMS weakens this capability through the significant impact of observational noise on warm‐core retrievals. In this study, a remapping algorithm is applied to obtain AMSU‐A‐like ATMS fields of view to suppress this noise. A modified warm‐core retrieval algorithm, which consists of two sets of training coefficients for clear‐sky and cloudy conditions, is applied to limb‐corrected ATMS and AMSU‐A measurements using collocated Global Positioning System radio occultation observations in the previous month of the targeted hurricanes as training data sets. ATMS channels 5, 6, and 7 (AMSU‐A channels 4, 5, and 6) are excluded when training the coefficients for cloudy conditions to avoid cloud/rain contamination. As a result, the abnormal cold core in the low and middle troposphere and the banded warm structures in phase with rainbands are both successfully removed. The warm‐core evolution of Hurricane Matthew (2016) during its entire life span is temporally consistent on intensity as obtained from NOAA‐15, NOAA‐18, and MetOp‐B AMSU‐A observations and S‐NPP ATMS observations.