ENKHTAIVAN BOLORTUNGALAG

Study of the Temporal Trends of Heavy Rain Cases in Various Observation Points in Summer, 2022 in Japan

Toshiro KUMAKURA

In this research, regarding the survey of heavy rainfall in various places in the summer of 2022 and the tendency of temporal concentration of precipitation. Precipitation accumulation time spans were taken from 1 hour to 48 hours, and the maximum precipitations for each time span was obtained at 7 observation points in July to August. The data used for the comparison were RADAR precipitation data from the weather RADAR and precipitation data from AMeDAS system operated by the Japan Meteorological Agency (JMA). We obtained the hourly rainfall data from the JMA website, and the RADAR rainfall data was obtained by putting together files created by the JMA and outputting the rainfall intensity of the target area. 
The AMeDAS data measured more precipitation than the weather RADAR data at all observation points. In RADAR observation, the intensity of precipitation is measured from the intensity of radio waves reflected by rain or snow particles. A situation may occur in which the precipitation is attenuated and observed as weaker than the actual precipitation. For this kind of reason, it is speculated that the RADAR precipitation amount was smaller than the AMeDAS precipitation amount. From the results of the comparison of the maximum precipitations for each time span between AMeDAS and RADAR to the 48-hour precipitation for each observation points, both the RADAR precipitation and the AMeDAS precipitation have changed in the same manner, except for Shimoseki.  It was found that there are cases where the maximum precipitation pattern differs, such as in Shimoseki and Osaki. In the analysis of heavy rainfall, it was found that the results were different if the geological position was shifted slightly, but it was also found that the maximum hourly rainfall shown as a ratio to the 48-hour rainfall had a similar tendency except for Shimoseki. As for Shimoseki, it is thought that the precipitation was different in characteristics from the others.