Author(s): Masato Kita, Yoshihisa Kawahara, Cho Thanda Nyunt
Linked Author(s): Masato Kita
Keywords: WRF (Weather Research Forecasting model), 3-D variational method, X-band radar, torrential rainfall
Abstract: Ministry of Land, Infrastructure, Transport and Tourism (MLIT) of Japan has operated X-band dual polarimetric radar network system having high spatio-temporal resolution to monitor heavy rains over big cities in Japan. The radar system has been contributing to the advancement in nowcasting while its application to short-range weather forecasting has been limited. This study aims to quantify the effects of the data assimilation interval using WRF (Weather and Research Forecasting) model coupled with a 3-D variational method for the torrential rainfall in Hiroshima City in August 2014. It is shown that band-shaped precipitation system at 1: 00 is predicted with X-band MP radar data assimilation and that data assimilation at 10-minute interval reproduces the area of heavy rainfall best. Comparison between the case with data assimilation at 10-minute interval and that without data assimilation explains that X-band MP radar data assimilation induces the favorable environment for convective rainfall to develop through modifying wind vectors and vapor fields
Year: 2017