边界层参数化方案对暴雨数值模拟的影响

Impact of Different Boundary Layer Parameterization Schemes on the Numerical Simulation for a Rainstorm

选取2003年7月4—5日南京暴雨个例,采用非静力中尺度模式MM5进行模拟,着重研究了不同边界层参数化方案对雨量中心强度、雨区分布的影响。结果表明:对于不同的边界层参数化方案,垂直速度场、水汽通量散度场、涡度场、水平风场的散度以及sθe场都表现出不同的特征;合理边界层方案的引入对预报效果有明显的改进;结合边界层和自由大气的动力、热力结构进行了综合分析,给出了边界层作用与自由大气动力、热力结构的配置情况,说明这种配置对暴雨的形成是至关重要的。

During the period of 4th to 5th July 2003, a rainstorm occurred in Nanjing, resulting in a severe flood catastrophe. Using the nonhydrostatic version of mesoscale numerical model MMS, the numerical simulation of the rainstorm is performed to emphatically study the impacts of different boundary layer parameter schemes on the rainfall intensity and distribution,and the results indicate that,as to different boundary layer parameterization schemes . the vertical velocity, divergence, vorticity, water vapor flux divergence, and θse fields all display different characteristics. The proper boundary layer parameterization scheme obvious improves on simulated results. After synthetically analyzing the combination of the boundary layer and the dynamic and thermodynamic structures of the free atmosphere, their allocation state is proposed and proved to be essential to the forming of rainstorms.