Analysis of SFMR-Derived and Satellite-Based Rain Rates over the Tropical Western North Pacific

Abstract

Aircraft-derived rain rates are obtained from the Stepped Frequency Microwave Radiometer (SFMR) operated on WC-130J in tropical cyclones over the western North Pacific during the Tropical Cyclone Structure 2008 (TCS-08) program and the Impact of Typhoons on the Ocean in the Pacific (ITOP) 2010 program. Rain rates from SFMR are compared to rain rates from the Advanced Microwave Scanning RadiometerEOS (ASMR-E) and the Tropical Rainfall Measuring Mission (TRMM) satellites when the passes occurred within plus-or-minus three hours of the aircraft times. The relative frequency distributions of SFMR-derived rain rates matched the distribution of AMSR-E rain rates over low- to medium rain rates. However, rain rates over 10 mm h-1 occurred more frequently in the satellite-based values. Because of the difference between SFMR and AMSR-E rain rates over medium intensities, the two rain rate distributions are found to be statistically different. Similar differences were found in comparisons between SFMR and the TRMM Microwave Imager (TMI)-based rain rates, and in comparisons between TMI and AMSR-E rain rates. Differences between the relative frequencies of rain rates larger than 10 mm h-1 resulted in the conclusion that the distributions of SFMR and TMI frequency distributions and AMSR-E and TMI are statistically different.