Numerical test of topography effect on rainfall amplification associated with typhoonHaikui

Using NCEP GFS data and WRF V3.4 model, the strong precipitation event in Anhui caused by typhoon Haikui was simulated.To study the topography effect on rainfall amplification of typhoon Haikui, orographic sensitive experiments were conducted by changing the terrain altitude in Dabie mountains area and mountainous area of South Anhui. The results are as follows. (1) The typhoon precipitation event is well simulated by WRF model. (2) The terrain altitude in Dabie mountains and south mountainous area of Anhui affect in different degrees on track, pressure and precipitation of typhoon Haikui. There are clear differences in typhoon track and precipitation simulated by different terrain altitudes. The intensity of precipitation center has a good correlation with the terrain, which indicates that the terrain impacts greatly on the amplification of precipitation. (3) The formation and development of the mesoscale convergence line and vortex are due to the mountainous terrain, which enhances the water vapor convergence. Furthermore, the low-level upward motion in control experiment is clearly stronger than in zero terrain experiment, which leads to a significant increase of precipitation in the middle and south area of Anhui.