“7.18”山东暴雨过程分析III:WRF模式边界层参数化方案对物理量场的影响

Analysis of“7. 18”Shandong Heavy Rainfall Process III: the Impact of WRF Model Boundary Layer Parameterization Scheme on Physical Quantity Field

[目的]分析不同边界层参数化方案对此次暴雨过程中物理量场的影响。[方法]利用WRF模式3.4版本,选取不同边界层参数化方案对"7.18"山东暴雨过程进行敏感性试验,分析不同边界层参数化方案对此次暴雨过程中垂直速度场、水汽通量散度场、相对湿度、对流有效位能和边界层高度等物理量场的影响。[结果]不同的边界层参数化方案对于暴雨过程中垂直速度场的空间分布及其中心强度具有显著的影响,从而使得降水中心的分布和强度发生变化。尽管不同边界层参数化方案模拟得到的水汽通量散度在水平分布与实际结果具有较好的一致性,但其在垂直分布、中心位置及其强度上存在明显的差异。不同边界层参数化方案引起的边界层高度和对流有效位能的差异与其引起的降水分布差异直接相关。[结论]WRF模式中不同边界层参数化方案对暴雨过程中不同物理量场模拟效果的影响较大,选择合适的边界层参数化方案能显著提高对物理量场的模拟效果。

[ Objective] The aim was to analyze effects of different boundary layer parameterization schemes on physical quantity field in the heavy rainfall process. [ Method] Using WRF mode 3.4 version, sensitivity test was conducted on ＂7.18＂ Shandong heavy rainfall process, effects of different boundary layer parameterization schemes on vertical velocity field, water vapor flux divergence field, relative humidity, con- vective available potential energy and boundary layer height were analyzed. [ Result] The results showed that different boundary layer parame- terization schemes have a significant impact on spatial distribution of vertical velocity and the strength of rainstorm center, so the location and strength of rainstorm center change. The simulated water vapor flux divergence accords with the actual results on the horizontal distribution, but its center location, vertical distribution and strength have significant differences. The convective boundary layer height and effective poten- tial energy are different in models with boundary layer parameterization schemes, which directly relate to the difference of precipitation distri- bution. [ Conclusion] Different boundary layer parameterization schemes in WRF mode have significant influence on simulation results of vari- ous physical quantity field in rainstorm process, using appropriate boundary layer parameterization scheme can improve simulation results of physical quantity field significantly.