GPM/DPR precipitation compared with 3.5-km-resolution NICAM simulations

Abstract:

This study aims to compare the GPM (Global Precipitation Measurement)-derived precipitation data with other precipitation products and numerical model simulations as the first step toward the possible use of GPM-derived precipitation data in numerical weather prediction through data assimilation. In February 2014, the GPM satellite was launched successfully and started observing global precipitation between 65S and 65N using the new DPR (Dual-frequency Precipitation Radar) sensor. The GPM/DPR observes three-dimensional meteorological echoes with Ku-band and Ka-band radars. It is among our interests how the precipitation data from GPM/DPR compare with other precipitation data. In this study, we compare the GPM/DPR precipitation data with simulated precipitation from the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) at a 3.5-km horizontal resolution. Precipitation products derived from GPM/GMI (GPM Microwave Imager) and GSMaP/NRT are also compared. We focus on two precipitation types from May to July, 2014: frontal precipitation cases and tropical cyclone cases. The spatial pattern of the frontal precipitation measured by GPM/DPR agrees generally well with those of the other precipitation data. However, GPM/GMI-derived precipitation is systematically less than that of the NICAM simulation. By contrast, the vertical structures are considerably different between GPM/DPR and the NICAM simulation. The simulated mixing ratios indicate snow and graupel at upper levels, but these are not captured by GPM/DPR. The tropical cyclones captured by GPM/DPR are simulated reasonably well by NICAM. Further investigations will be made and will be included in this presentation.