WRF云微物理参数化方案对新疆暴雨模拟能力的TS评分分析

在中尺度数值模式中,选用不同的参数化方案对降水的模拟和预测效果会有很大影响,合理选择参数化方案可以提高预测准确性。为此,本文使用中尺度预报模式WRF 3. 8 (weather research and forecasting model,WRF)版本,采用3 km和9 km两层嵌套网格,利用ECMWF(European Centre for Medium Range Weather Forecasts)再分析资料作为初始场和边界条件,对新疆地区4次暴雨过程进行模拟,采用TS (threat score)评分评估了Lin方案、WSM6方案、Thompson方案和WDM6方案4种云微物理参数化方案对新疆地区暴雨模拟的适用性。结果表明:Thompson方案在站点降雨量为小雨(0. 1～5. 0 mm)和中雨(5. 1～10. 0 mm)的预报模拟中具有优势,其他3种云微物理参数化方案均在不同程度上存在漏报情况,从相关系数上判断,Thompson方案模拟效果略优于其他方案,适用于多小雨、中雨的新疆地区,但4种云微物理参数化方案在大到暴雨降水等级的预报效果都不是很好,这也正是WRF模式在新疆地区需要改进的地方。

TS Score of WRF Cloud Microphysical Parameterization Scheme to the Simulation Capability of Precipitation in Xinjiang

In the weather research and forecasting model, different parameterization schemes affect significantly the precipitation prediction. It can improve the prediction accuracy to choose the appropriate parameterization schemes. In this paper, the 3.8 version of WRF (weather research and forecasting model) was used to simulate four precipitation cases in Xinjiang using 3-km and 9-km two-layer nested grids and ECMWF (European Centre for Medium Range Weather Forecasts) reanalysis data as the initial fields and boundary conditions. The applicability of Lin scheme, WSM6 scheme, Thompson scheme and WDM6 scheme to precipitation simulation in Xinjiang is evaluated by TS (threat score) score. The results showed that the Thompson scheme was of an advantage in predicting light rain (0.1-5.0 mm) and moderate rain (5.1-10.0 mm), and there were the missing forecasts on rainfall by other three schemes of cloud microphysical parameterization. According to the correlation coefficient, the simulation accuracy of Thompson scheme was slightly higher than that of other schemes, this scheme was suitable for Xinjiang, but the four kinds of schemes were not very good in forecasting heavy precipitation, so the schemes need to be improved for Xinjiang.