地形对台风“海葵”降水增幅影响的研究

Numerical test of topography effect on rainfall amplification associated with typhoon Haikui

使用NCEP GFS资料和WRF V3.4模式对2012年第11号台风"海葵"(1211)引发的安徽强降水过程进行数值模拟,通过改变模式中安徽省大别山区和皖南山区的地形高度,设计一组敏感性试验,对"海葵"降水的地形增幅效应进行研究。结果表明:(1)WRF模式对台风"海葵"降水过程有较好的模拟能力。(2)大别山区和皖南山区地形对"海葵"移动路径、强度以及降水分布、强度均有不同程度的影响;不同地形高度下模拟的台风路径及降水分布差异较大,且降水中心强度与地形高度相关性较好,地形对暴雨增幅作用明显。(3)山区地形有利于中尺度辐合线和低涡生成、发展,并有强水汽辐合中心与之相对应;有地形时对流层低层上升运动比无地形时明显加强,对安徽中南部强降水增幅作用显著。

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 moun-tainous 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.