高分辨率GRAPES模式中云微物理方案对强降水的模拟和诊断研究

Simulation and Analysis of Heavy Precipitation Using Cloud Microphysical Scheme Coupled with High-Resolution GRAPES Model

利用高分辨率GRAPES—Meso中双参数云微物理方案,对我国两次强降水过程进行数值模拟,并与模式中WSM6和NCEP5方案进行对比分析,结合多种观测资料,诊断评估方案的预报性能.同时研究伴随强对流性降水中的关键云物理过程。个例研究表明,对流发展旺盛的云团中,冰相粒子尤其是霰粒子对对流的发展与降水起着主导作用,霰的融化是强降水的主要来源,而周围的层状云区域霰粒子的分布极少,主要受雪的融化与暖云降水的影n向。双参数方案模拟的雨带走向、范围和降水强度与实况拟合较好,同时在对流单体的最大回波高度与强度、冰晶的分布与云砧结构等方面也具有一定优势,但冰晶含量和回波顶高度略低于观测,这都为双参数方案的优化与业务应用提供重要的支持。

In this study, two heavy precipitation processes are simulated using the two-moment cloud mierophysical scheme coupled with high-resolution GRAPES model. The scheme is compared with WSM6 scheme, NCEP5 scheme and a variety of observation data to diagnose the prediction performance and analyze the key cloud microphysics process in deep convective precipitation. The simulation study shows that ice phase particles, especially graupel particles, play a leading role on the convection and precipitation in the deep convection clouds and the melting of graupel is the main source of heavy precipitation, while graupel distributes rarely in the stratiform precipitation region which is mainly affected by the melting of snow and warm cloud precipitation. The results derived from the two-moment scheme fit better with observations on rain belt direction, precipitation range and intensity. The scheme also has certain advantages on the maximum echo height and strength of convective cells, ice content distribution and cloud anvil structure. However, the ice content and echo height are slightly lower than observations. All these results would provide meaningful support for the improvement and operational application of the two-moment scheme.