Numerical Study Of The Heavy Rain Process In The Western Part Of Sichuan Basin During August 2003

China is a typical country affected by the monsoon climate,the heavy rain often causes disasters during the summer monsoon season.Due to the vast territory and the complicated topography, the properties of precipitation vary from region to region. There exists an isolated center of heavy rain in the category of climatology that locates in the western Sichuan basin to the east of the Tibetan Plateau. The background field of circulation, period of time and type related to the precipitation of this area differ significantly from those of the eastern China of the same latitude, so we focus on the precipitation properties of this area in this paper.Advanced Regional Eta-coordinate Model (AREM) was developed by Institute of Atmospheric Science, China Academy of Science (IAP/CAS). AREM is a numerical model that aims at the solution of steep topography areas and it proved to be an effective model tool to study the precipitation of steep topography areas. AREM is adopted to study the heavy rain case of western Sichuan basin which occurred during Aug. 2003.1 Base on datum ,we further confirm that during the precipitation processes, the macroscale circulation and local atmospheric properties have the following features:1) The South Asia high is stronger than normal and with its center shifts eastward and the ridge shifts northward.,and the western Pacific subtropical high extends westward and northward. 2) During the process of heavy rain, low-level air is the warm and humid with unstable atmospheric stratification.The topographic convergence of low level Apheliotes in the west of the basin is a main factor that contributes to the local precipitation.2 We use AREM to simulate the precipitation of Chuan-Xi area, taking the station observational data as the initial field, AREM can well reproduce the weather features of the precipitation in Aug. 2003, that validate the model's...