Drop Size Distribution Observed by Dual-frequency Precipitation Radar onboard Global Precipitation Measurement Core Satellite

This study investigated the drop size distribution (DSD) observed by the Dual-frequency Precipitation Radar (DPR) onboard the Global Precipitation Measurement (GPM) core satellite, which makes the world's first dual-frequency preciptation observations by space-borne radar. Four years have passed since the launch of the GPM core satellite, and data have been accumulated. This study focuses on the characteristics of DSD derived from the GPM/DPR measurements. In this study, DSD parameters (especially for a mass-weighted mean diameter, Dm) which are estimated based on dual-frequency information derived from GPM/DPR are analyzed with seasonal variations and precipitation characteristics. Values of Dm are generally larger over land than over the oceans. DSD shows seasonal variation, especially over the mid-latitude ocean; Dm in the winter season over the mid-latitude ocean is larger than that in the summer season in both the Northern and Southern hemispheres. Focusing on the mid-latitude North Pacific Ocean close to Japan in winter, precipitation top height is lower and stratiform ratio is higher than those in summer. It suggests that differences of Dm are associated with those of precipitation regimes, such as organized precipitation system in summer season and extratropical frontal systems in winter season.