CHARACTERISTICS OF PRECIPITATION SYSTEM IN HIROSHIMA PREFECTURE DURING THE HEAVY RAINFALL EVENT OF JULY 2018 USING XRAIN DATA

Abstract

 Heavy rainfalls with band-shaped precipitation systems attacked the western part of Japan from June 28 to July 8, 2018, causing flood and sediment disasters in Hiroshima Prefecture. MLIT (Ministry of Land, Infrastructure and Transport) has operated XRAIN (eXtended RAdar Information Network) that consists of X-band MP radars and C-band MP radars.

 In this study, we show the meteorological conditions using the MesoScale Model and report the observed results in Hiroshima Prefecture during the heavy rainfall. It is confirmed that XRAIN can observe the spatio-temporal distribution of rainfall intensity with high accuracy compared with rain gauges. 3-dimensional rainfall intensity is interpolated using two X-band MP radars and describe the structure of the band-shaped precipitation system. As a result, it is shown the cloud top of the band-shaped precipitation system reached less than 8,000 m, which was lower compared with heavy rainfall on August 20, 2014. In addition, the band-shaped precipitation system observed around Hiroshima Station at 18:05 on July 6, 2018 has higher rainfall intensity than other band-shaped precipitation systems because of the water vapor supply from the south and atmospheric instability.