中尺度多模式超级集合预报对2010年6月19—20日中国南方大暴雨过程的分析

ANALYSIS OF A HEAVY RAIN PROCESS ON JUNE 19—20,2010 IN SOUTHERN CHINA BY USING A MULTI-MODE MESOSCALE SUPER-ENSEMBLE FORECASTING SYSTEM

运用BGM扰动方案,基于ARPS和WRF模式并采用不同的物理过程参数化方案建立了一个多模式、多初值、多物理过程的中尺度超级集合预报系统,并针对2010年6月19—20日的一次华南强降水过程进行分析。结果表明:该超级集合预报系统能很好模拟这次对初值及物理过程都非常敏感的强降水过程。相对于单一确定性预报而言,该超级集合预报能显著提高预报时效,能比控制预报提前24～36小时捕捉到强降水信息。并且该集合预报优于单一模式或者单一物理过程参数化的集合预报。对本次过程而言,集合平均对物理过程参数化方面带来的不确定性的改进比对模式不确定性方面的改进大得多。对于暴雨预报而言,低层的形势场对初值及物理过程的扰动比高层要敏感得多,这也是造成这次过程各个成员预报好坏的重要原因之一。

A mesoscale super-ensemble forecasting system, with the characteristic of multi-mode, multi-initial values and multi-physical processes, is established based on ARPS and WRF. Moreover, and a program of dual BGM disturbance and different parameterized programs of physical processes are simultaneously utilized. Besides, a heavy rainfall in the south of China which occurred on June 19--20, 2010 is analyzed with it. The result indicated that the super-ensemble forecasting system, which is highly sensitive to the initial value and physical processes, could well simulate this precipitation process. For a single deterministic prediction, the period of validity would be improved so that strong rainfall information could be captured 24 ~ 36 hours earlier than the control system, if this forecasting system is put to use. In addition, the prediction of this kind of ensemble is better than that based on a single model or a parameterized program of a single physical process and parameterized programs of physical processes are amended more than models. In terms of storm rainfall prediction, physical processes and initial values are more sensitive to the disturbance of the low-level than that of high-level, and this may be one of the most important reasons why the forecasting results of some members are better than those of others.