A new Dual-Frequency-based Hydrometeor Classification Approach for the Global Precipitation Measurements Core-Satellite

This study introduces a new three-dimensional hydrometeor classification (HMC) based on the measurements of the dual-frequency precipitation radar (DPR) on board of the core satellite Global Precipitation Measurement (GPM) towards a more detailed satellite-based and thus area-wide classification. To establish the new dual-frequency-based HMC method (HMC-DF), measurements from several overflights of the GPM satellite are directly compared with the dual polarisation measurements of the C-band radar network of the German Weather Service (DWD). The DPR measurements are assigned to hydrometeor classes determined via existing polarimetric HMC applied to the ground-based measurements. For the specific hydrometeor classes, the reflectivities at Ku-band, at Ka-band and the dual frequency ratio (DFR) are considered as three-dimensional vectors and averaged to centroids. The determined centroids are used to assign current DPR measurements to a specific hydrometeor class based on the euclidean distance between observations and centroids. Vertical distributions of hydrometeor types derived from ground-based polarimetric measurements of the X-band weather radar BoXPol operated by the University of Bonn in western Germany are used for a first evaluation of the new dual-frequency-based HMC and confirms its applicability.