Accuracy Assessment of Global Satellite Mapping of Precipitation (GSMaP) by Small Precipitation Radar Constellation

抄録

The concept of a small precipitation radar constellation has been proposed by the Japan Aerospace Exploration Agencyas one of the future precipitation observation missions. If realized, this can improve the quality of the Global Satellite Mapping of Precipitation, or GSMaP. This study evaluated the impact on the accuracy of GSMaP resulting from increased spaceborne radar　observations over Japan. The Japan Meteorological Agency provides high-accurate and high-resolution ground precipitation radar data calibrated by rain gauges. These ground observation data were used to generate the pseudo future precipitation radar data and inserted into the operational GSMaP processing in some temporal intervals. Both the sampling errors and retrieval errors were taken into consideration by utilizing Dual-frequency Precipitation Radar aboard the Global Precipitation Measurement Core Observatory. The relationship between temporal interval of insertion to the GSMaP processing, and improvement of GSMaP accuracy were verified. Results indicated that accuracy improved as pseudo Precipitation Radar (PR) data were inserted into the GSMaP processing more frequently. Furthermore, the GSMaP accuracy improved not only with the time when the pseudo PR data was inserted but also several hours after the insertion, which can be due to the characteristics of the GSMaP algorithm.