利用中尺度模式WRF对2011年9月29-30日1117号强台风“纳沙”登陆并穿过海南岛北部引发的海南岛西部特大暴雨过程进行了数值模拟和地形敏感性试验。结果表明，在海南岛北部登陆西行的台风降水量分布呈五指山以北地区多、 以南地区少的特征，而北面的强降水带又是西部多、 东部少。12 km水平格距模拟的48 h降水量和逐3 h降水量与实况基本相符，台风登陆时间与地点误差也较小，路径和强度模拟效果均较好。对比控制试验和地形敏感性试验模拟的24～48 h降水量发现，有地形时，海南岛西部地区24 h降水量普遍有50 mm以上的增幅，西部山区有150 mm以上增幅，西部山区主峰北侧有350 mm增幅。特别是强降水中心与西部主山峰紧密相连，地形的存在对台风“纳沙”在海南岛西部地区的降水量增幅明显。但受五指山脉地形的阻挡，处于台风环流中西北气流背风坡的海南岛东南部地区降水量有50～150 mm的减幅。从低层中小尺度流场和垂直速度的对比分析可以看出，控制试验与零地形试验结果存在明显差别，五指山脉西部的地形可以增强低层扰动，有利于产生中尺度对流小涡，从而增加台风降水。王下乡的特殊地形对台风降水显著偏多起到重要作用。

Numerical simulation and terrain sensitivity experiments on the heavy rainfall caused by the typhoon Nesat during 29-30 September 2011 were studied using the weather and research forecast(WRF) model when Nesat made the landfall and went through the north Hainan Island. The results show that: The rainfall caused by the westing typhoon landfall on the north area distributed more in the north than the south. In the north, there is more rain in the west area than east area. 48 h and 3 h accumulative rainfall from the 12 km experiment are successfully modeled and the landing time and location is close to the observed. The typhoon track and intensity are good simulated as well. The terrain sensitivity experiment shows that 24 h precipitation from the experiments with terrain have increased generally by more than 50 mm in the west area in Hainan Island. Increase of more than 150 mm has been observed in the western mountainous regions, with 350 mm increase in the north part of the main peak. Heavy precipitation center is found responding to main mountain peak, It proves that, the terrain can result in general obvious rainfall increase in typhoon. However, there is a 50~150 mm rainfall reduction in the eastern coast of the island due to the block from the Wuzhishan Mountain. Analysing the comparison of low-level mesoscale flow field and the vertical velocity, significant difference can be found between control experiments and experiment with none terrain. The Wuzhishan terrain can enhance low-level disturbances, which can easily produce the vortex of mesoscale convection (MCS), then by increasing the typhoon rainfall. The special terrain of Wangxia plays an important role in increasing the typhoon rainfall.