[A-AS08] Multiple scale structure and their interactions in Asian monsoon system

[AAS08-07] Analyzing spatiotemporal continuity in Asian precipitation data obtained using spaceborne precipitation radars

*広瀬 正史¹ (1.名城大学)

キーワード：衛星搭載降水レーダ、降水システム気候学、サンプリング充足度

This study examines updates of various long-term spaceborne radar records of the mean Asian precipitation, with particular focus on spatiotemporal variability. Using the Precipitation Radar (PR) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite, precipitation data for low and middle latitudes from January 1998 to September 2014 are obtained. The entire TRMM PR dataset and seven years of the Ku-band radar precipitation estimates obtained from the Dual-Frequency Precipitation Radar (DPR) onboard the Global Precipitation Measurement (GPM) Core Observatory are employed herein. The sampling properties of the combined data differ in terms of the latitude and period. The number of DPR samples for each month has been reduced by a third of that of PR samples around Japan near the northern edge of the TRMM orbit. These products are both based on the DPR 06A algorithm, exhibiting similar statistics in terms of the incidence-angle dependency, which is a dataset-specific feature. The globally averaged precipitation is slightly higher for DPR than for PR; however, on a regional scale, the systematic bias is difficult to distinguish based on the sampling variability. The sampling sufficiency can be inferred from several indicators, such as the number of satellite overpasses, total number of large-scale precipitation systems, and the detection rate of spatiotemporally coherent diurnal signatures. Herein, a spaceborne radar-captured precipitation system (SR-PS) database is prepared at a resolution of 0.1 degree to decompose the precipitation characteristics into groups. The attached figure indicates the time-varying precipitation attributed to SR-PSs at various spatial scales around the foothills at the south of the Himalayas (24-29N and 77-90E). The figure shows the seasonal variations in the primary rainfall peak around dawn, associated with widespread systems, and in a secondary peak in the afternoon by smaller systems. By increasing the number of data samples of significant events, the combination of the TRMM and GPM data improved the sampling sufficiency more noticeably for precipitation in pre-monsoon season than in the mature monsoon season. The impact of data accumulation on spatiotemporal continuity of mean precipitation varied considerably based on the region and season.