一次强对流的三维数值模拟分析

THREE-DIMENSIONAL NUMERICAL SIMULATION OF A SEVERE CONVECTIVE STORM

利用中国科学院大气物理研究所的完全弹性三维雹云数值模式(IAP-CSM3D),对2007年7月21日发生在湛江的一次强对流进行数值模拟,分析了强对流的气流结构、垂直涡度、雷达回波及含水量分布变化特征。结果表明,模拟的回波最大强度与雷达实测结果较吻合。模拟的强对流发展阶段气流结构的典型特征为下层水平辐合,上层水平辐散,气流在5 km高度发生转向;处于成熟阶段的底层辐合比发展阶段的更强。随着时间的推移,近地层气流先辐合后辐散,下沉辐散气流一直持续到冰雹云消散。模拟的风暴云高含水量中心与强回波中心相对应,出现在上升气流最大区域附近,这说明该风暴云的动力场与物质场配合较好。

Using the fully elastic three-dimensional convective storm model （IAP-CSM3D） developed in Institute of Atmospheric Physics,Chinese Academy of Sciences （IAP）, the July 21, 2007 Zhanjiang severe convective storm was simulated and its flow structure, vertical vorticity, radar echo, together with the characteristics of water content variation, were analyzed. The results showed that the simulated maximum refleetivity was coincident with the observation result. The simulated flow structure during the storm＇s development stage was characterized by low-level convergence and high-level divergence with the flow shifting its direction at 5 km. The convergence during the mature stage was more significant than that during the development stage. With the passage of time, the surface layer flow turned from convergence into divergence and the divergent downdraft lasted till the storm dissipated. The simulated core of the storm water content relative to the core of radar reflectivity was near the maximum updraft area, which indicated that the dynamic field agreed well with the material field.