Distribution of Precipitation Depending on Synoptic Scale Disturbances with Satellite Estimate Comparisons in the Japanese Alps Area during Warm Seasons

Abstract

 Gauge-based hourly precipitation data during the 2015-2016 warm seasons in central Japan observed with the Japan Meteorological Agency AMeDAS network and the Japanese Alps Inter-University Cooperation Project (JALPS) mountain observation network are archived. Gauge data are compared to satellite precipitation data (GSMaP_MVK and GPM/DPR) produced by Japan Aerospace Exploration Agency. The distributions of precipitation measured in gauges depend on synoptic scale disturbances showing areas of regional increases/decreases affected by large mountain ranges without year-to-year variability, except for a composite of typhoon cases. Differences in precipitation amounts are less than 2 mm/d depending on satellite product version or timing of passive microwave observations. Larger precipitation amounts of GSMaP_MVK estimated at more than 2 mm/d are distributed over inner mountain areas and northern coastal areas along the Sea of Japan, and larger amounts of gauge-measured precipitation are distributed in central Gifu and Shizuoka Prefectures. The underestimate of local sporadic heavy precipitation in mountainous areas obtained from GSMaP_MVK data was expected depending on shallow convections. Further strategies are discussed for conducting case studies to reveal the causes of discrepancies between gauge-measured and satellite-indicated precipitation.