GPM/DPR Precipitation Compared with a 3.5-km-Resolution NICAM Simulation

Abstract

In February 2014, the Global Precipitation Measurement (GPM) satellite was launched successfully and started observing global precipitation using the new DPR (Dual-frequency Precipitation Radar) sensor. This study pioneers to compare the GPM/DPR precipitation products with other satellite-derived products and simulated precipitation from the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) at a 3.5-km horizontal resolution. The NICAM simulation outputs are converted to three-dimensional radar reflectivity using a radar simulator included in the joint simulator for satellite sensors (Joint-Simulator). We focus on the three frontal precipitation cases in the storm track regions, where the NICAM surface precipitation agrees generally well with an existing precipitation product “GSMaP”. The surface precipitation patterns, bright band heights and three-dimensional radar reflectivity of GPM/DPR generally agree with the corresponding variables from GSMaP, NICAM and the Joint-Simulator. However, the radar echo tops of GPM/DPR are systematically lower than that of NICAM-Joint-Simulator, suggesting that NICAM may overestimate mixing ratios of snow and graupel. The general agreement of surface precipitation patterns between GPM/DPR and the NICAM simulation encourages a possible use of GPM-derived precipitation data toward numerical weather prediction through data assimilation.