Statistical analysis of simulated direct and indirect precipitation associated with typhoons around Japan using a cloud-system resolving model

Abstract

To validate the reproducibility of simulated typhoons and related precipitation, perfect boundary condition experiments, forced by 20-km-mesh Japan Meteorological Agency (JMA) operational regional ob- jective analysis (RANAL) data from June to October in 2002‒2006, are performed using a 5-km-mesh cloud- system resolving nonhydrostatic regional climate model (NHM-5km). NHM-5km reproduced all 57 typhoons observed in the model domain during the experiment period. Relative to JMA best track data for the typhoons, the average position error of typhoon centers is 130 km at 72 hours after typhoon genesis or when the typhoon first enters the model domain. The simulated minimum central pressures of typhoons are similar to those in RANAL data. The precipitation within (outside of) a 300-km radius from the center of each typhoon is defined as direct (indirect) precipitation. The distribu- tions of the simulated direct and indirect precipitation of typhoons show good agreement with precipitation analyses by JMA. For hourly precipitation amounts ex- ceeding 5 mm, direct precipitation is observed more fre- quently than is indirect precipitation, especially for amounts exceeding 20 mm. These features are well re- produced by NHM-5km. The appearance frequency of simulated direct precipitation for hourly precipitation amounts also shows a good quantitative agreement with that measured by raingauges.