NUMERICAL SIMULATION OF A TORRENTIAL RAINFALL EVENT OCCURRED AT ITABASHI ON JULY 5, 2010

Abstract

Torrential rainfall events often brought sudden flood and damages especially in urban area. However, it is still hard to forecast the occurrence of torrential rainfall. In this study we analyzed evolution process of a torrential rainfall event that was occurred at Itabashi, Tokyo, on July 5, 2010, to accumulate knowledge of developing mechanism and possibility of forecast of this type of rainfall. The regional meteorological model, WRF (Weather Research and Forecasting), reproduced the torrential rainfall event fairly well by the use of JMA-MSM (Japan Meteorological Agency-Mesoscale Model) data as initial and boundary conditions. For the development and maintenance of the rainfall, three streams of see-breezes from Sagami bay/ Tokyo bay/ Kashima Nada played a key role in accumulating moisture and supplying it into the precipitating system. The model reproduced the sea-breezes well, that is why it could reproduce the rainfall well.