中文摘要：

数值模式能否准确地对降水过程进行预报，很大程度上取决于云微物理参数化方案能否准确地对云内的物理过程进行描述。目前显式云微物理参数化方案中对粒子的下落速度、不同直径粒子的浓度分布两方面的微物理特征，分别使用质量加权下落末速度和粒子谱进行描述。因此，参数化方案中不同的描述方式直接影响数值模式对降水过程的模拟结果。本文使用耦合了一种新的体积水法双参数云微物理参数化方案的WRF模式（Weather Researchand Forecasting Model）3．5．1版本对发生在2013年5月8目的一次华南强降水过程进行模拟，分别对Ferrier和Locatelli两种质量加权下落末速度计算方法，以及常数参数和根据东亚地区实际观测结果改进的谱形参数两种粒子谱形参数设置的模拟结果进行分析，并对他们的四组参数组合预报结果进行评估。结果表明：（1）质量加权末速度的改变对降水强度有一定影响；（2）粒子谱形参数对模拟降水的强度和发展都有明显的影响，且谱形参数对本次降水模拟的影响强于下落末速度的影响；（3）Ferrier质量加权末速度和改进的谱形参数的组合试验组对降水的预报效果，相对其他三组试验有较明显的优势。

英文摘要：

The accuracy of numerical weather prediction is mainly affected by the description of physical processes in cloud microphysics schemes. In current microphysical parameterizations the fall speed and diameter-concentration distribution of hydrometeors are described using the mass-weighted terminal velocity and drop size distribution shape parameter. Therefore,the description in different schemes directly influences numerical weather prediction. In this study, the Weather Research and Forecasting （WRF） model （version 3.5.1）, coupled with a new bulk two-moment microphysics scheme, was used to simulate a severe precipitation event that occurred in South China on 8 May 2013. Two descriptions of terminal velocity, two descriptions of the size distribution parameter, and four combinations of each, were evaluated and analyzed. The results were as follows： （1） Changes in snowfall terminal velocity had certain impacts on precipitation intensity; （2） Changes in the size distribution shape parameter generated more obvious impacts in terms of both the intensity and development of precipitation; （3） Combining the Ferrier mass-weighted terminal velocity and the improved size distribution shape parameter, using long-term observations in East Asia, showed clear advantages compared with three other sensitivity runs.