中文摘要：

文章利用中尺度模式WeatherResearchandForecastingModel（WRF）3．2．1版本及NationalCentersforEnviron—mentalPrediction（NCEP）分析资料，研究了陆面变量（土壤湿度、土壤温度）和陆面参数（植被覆盖率）初始场随机扰动对长江中下游暴雨预报的影响并进行了集合预报试验。试验结果表明，短期暴雨过程对陆面变量（参数）扰动是敏感的；陆面变量（参数）初始场扰动影响降水的时间尺度小于10h甚至可以小于6h。从影响机理上来看，陆面变量（参数）扰动首先改变地表的潜热通量和感热通量，而地表通量的改变会通过陆气相互作用对局地大气的温、压、湿、风产生较大影响，从而对暴雨的强度和落区产生较大影响。集合预报结果表明，利用陆面变量（参数）扰动制作集合预报，预报的集合平均结果要好于控制预报的结果，且比集合成员稳定可靠，降水概率预报可以提供一些有用的信息，对预报强降水有一定的指示意义。在初值集合预报中，以这些参数或变量的扰动来引进集合成员是十分有意义的。

英文摘要：

The simulation of a heavy rainfall event that occurred in the middle and lower reaches of Yangtze River was conducted to examine the effects of perturbations of land surface variables （soil moisture and soil temperature） and land surface parameter （vegetation fraction） in the ensemble forecast using the Weather Research and Forecasting Model （WRF） Version 3.2.1 and National Centers for Environmental Prediction （NCEP） reanalysis data. The results showed that land surface variable （or parameter） perturbations have a large impact on short-term simulation of rainstorm. The time scale that the land surface variable （or pa- rameter） perturbation affects precipitation is lower than 10 h and the smallest time scale is lower than 6 h. From the point of influence mechanism, disturbance of the land surface variables （parameters） changes the surface latent heat flux and sensible heat flux firstly, which has great impact on the local atmospheric tem- perature, pressure, humidity and wind field by the land-atmosphere interaction, and thus affects the inten sity and distribution of the heavy rainfall. ~i2he ensemble average result is better than the control forecast, which is more stable and credible than the single ensemble members. The analysis of the precipitation probability forecast can provide some useful information about the precipitation forecast especially to heavy rainfall. Overall, the initial perturbation of land surface variables and land surface parameter perturbations are significant to the initial ensemble forecast.