偏波レーダー立体観測情報の活用による地形性降雨算定手法の改良

Abstract

Japan has many steep terrains and mountains increase rainfall, resulting in higher total rainfall. As a result, there is sometimes a discrepancy between radar-observed rainfall and ground-observed rainfall. Accurate estimation of ground rainfall is very important for disaster management. In this study, values of the capture rate calculated from polarization parameters observed by radar at multiple altitudes were used in a topographic rainfall model to improve the accuracy of ground-based rainfall estimation. As a result, the accuracy was improved compared to using radar information from only a single altitude. The reduction of the capture rate due to wind in ground rain gauges was also checked, and it was confirmed that there is a sufficient possibility of errors in the rain gauge values that have been assumed to be positive so far. Furthermore, a detailed check of the values of cloud water content in the calculation process of the topographic rainfall model revealed that an accurate representation of water vapor content has a significant influence on rainfall.