Original paper
Comparison between precipitation estimates of ground-based weather radar composites and GPM's DPR rainfall product over Germany
Pejcic, Velibor; Saavedra Garfias, Pablo; Mühlbauer, Kai; Trömel, Silke; Simmer, Clemens
Meteorologische Zeitschrift Vol. 29 No. 6 (2020), p. 451 - 466
66 references
published: Nov 25, 2020
published online: Jul 17, 2020
manuscript accepted: Jun 8, 2020
manuscript revision received: Jun 8, 2020
manuscript revision requested: May 22, 2020
manuscript received: Apr 17, 2020
Open Access (paper may be downloaded free of charge)
Abstract
We compare more than three years (between 2014 and 2018) of precipitation estimates over Germany from the Dual-frequency Precipitation Radar (DPR) operating on the core satellite of the Global Precipitation Mission (GPM) with the radar-derived precipitation product RADOLAN RY provided by the German national meteorological service (DWD, Deutscher Wetterdienst). Incomplete overlap between the observation volumes due to the different scan geometries and inconsistencies related to the mutually assumed hydrometeor phases lead to large differences, when directly comparing DPR's near surface product (DPRns) with RADOLAN RY. We improve the correspondence between both data sets via two steps. First, we derive an adjusted DPR near surface product (DPRans) extracted from the DPR vertical profiles, that best fits to the scans height and beam width of the surface radar observations. Second, the data is classified into liquid, solid and mixed phases by adjusting hydrometeor phase classification (aHPC) to the RADOLAN scan geometry. With these steps the correlation between both data sets increases from r = 0.49 to r = 0.61 and the RMSD is reduced from 2.94 mm/h to 1.83 mm/h for the commonly observed precipitation, exceeding most of the results found in previous studies. The agreement is best in stratiform precipitation (r = 0.68, RMSD = 1.4 mm/h), for only stratiform and summer season (r = 0.7, RMSD = 1.59 mm/h), and for stratiform with only liquid precipitation (r = 0.67, RMSD = 1.58 mm/h). Unlike the the standard DPRns, the new DPRans product exhibits almost no seasonal differences in the capability of detection; for all seasons the CSI is 0.94 and the FAR/IFAR are 0.04/0.02.
Keywords
GPM DPR • RADOLAN • satellite rain rate • surface precipitation