THE HYDROMETEOR IDENTIFICATION FOR THE GPM DPR: Version 8 Updates

Since May 2018, the Dual-frequency Precipitation Radar (DPR) on board the GPM core observatory satellite has operated in full scan mode. Dual-frequency full swath data provides us a valuable chance to improve our knowledge of precipitation processes by providing greater dynamic range, more detailed information on microphysics, and better accuracies in rainfall and liquid water content retrievals [1]. The DPR Level-2 algorithms consist of several modules including the classification (CSF) module, where precipitation type is classified into three major types: stratiform, convective, and other.  Besides that, estimates of the melting layer top and bottom are provided in the classification module with product name as “binDFRmMLTop”, “binDFRmMLBottom” and the quality metric of “flagMLquality”. Three flags namely, identifiers of falling snow on the ground, graupel or hail along vertical profile termed, “flagSurfaceSnowfall”, “flagGraupelHail” and “flagHail” are recently developed in the DPR level-2 algorithm using a concept of precipitation type index (PTI). All these are currently developed products (version 7) in classification module of GPM DPR level-2 algorithm based on full-swath dual-frequency observations [2][3][4]. 

 

In near future, a new feature will be added to the version 8 of the GPM DPR level-2 algorithm to provide vertical profile of hydrometeors for full swath data.  A conceptual flow  for initial implementation will be presented. The judgements are made mainly on the DPR products omly to provide an independednt assessment. Mixed phase hydrometeors are judged with melting layer top and bottom together with the 0° isotherm. Flag of surface snowfall is used to identify snow only profile, while flags for detecting graupel and hail help identify range bins with those hydrometeor types. The whole judgement  a robust detection system to not only combine the products but enforce meteorologically meaningful. In the initial phase, five hydrometeor types will be introduced. They are dry snow/ice crystal (DS/ICE), wet snow (WS), graupel (GPL), hail (Hail) and rain (Rain). DS/ICE, GPL and Hail represent low-density, medium-density, high-density particles respectively.