Global and monthly diurnal precipitation statistics based on passive microwave observations from AMSU

This paper presents climatological studies of precipitation-rate estimates based on data from the Advanced Microwave Sounding Unit instruments, AMSU-A and AMSU-B, aboard the NOAA-15, NOAA-16, and NOAA-17 satellites; and the corresponding set of instruments, AMSU and the Humidity Sounder for Brazil (HSB), aboard the NASA Aqua satellite. A precipitation-rate retrieval algorithm for these instruments has been developed (Chen and Staelin, IEEE Trans. Geosci. & Remote Sensing, 41(2)). This algorithm relies primarily on the opaque microwave bands near 54 and 183.31 GHz which correspond to oxygen and water vapor absorption bands, respectively, while most efforts towards satellite-based passive microwave remote sensing of precipitation (e.g. using TMI, SSM/I, and AMSR-E data) have relied primarily on window channels. The AMSU algorithm has shown promising agreement with NEXRAD over the eastern U.S. and plausible results globally. The NOAA-15, NOAA-16, and NOAA-17 satellites are polar-orbiting with equatorial crossing times of approximately 7 AM/PM, 2 AM/PM, and 10 AM/PM, respectively. The AMSU-A/B's aboard these satellites are able to observe each point on the globe approximately six times a day, and the sun-synchronous positioning permits meaningful study of the diurnal variations of precipitation. Maps of climatological statistics such as rain averages, rain frequencies, diurnal variations based on rain averages, and diurnal variations based on rain frequency will be presented for the period from June 2002 to January 2004.