摘要:使用中尺度数值模式WRF中的双参数云微物理方案WDM6针对2008年台风“凤凰”登陆过程中造成的强降水进行数值模拟，通过卫星模拟器利用MTSAT-1R和TRMM卫星观测的红外云顶黑体亮温TBB、PR雷达反射率资料使用统计方法验证模拟结果。通过修改云水向雨水自动转化过程、冰晶核化过程、雪和霰的下落末速度、雪和霰的截距进行敏感性试验，减小模拟结果和卫星观测结果的差异。研究结果表明：WDM6方案模拟的台风“凤凰”登陆后的降水，强对流云系及对流柱状雷达回波基本符合实况，但模拟结果局部偏强。WDM6方案模拟产生了较多的浅对流云，低估了对流云系的出现频率。不同云类型模拟的雷达回波均偏强，对流云系雷达回波垂直分布接近观测。敏感性试验结果说明修改WDM6方案中云水向雨水自动转化率有效地改善了模拟效果。同时发现云滴初始数浓度影响云水向雨水自动转化率并最终影响云系结构和雷达反射率的模拟结果，过高的云滴初始数浓度会使模拟结果变差。
关键词:WRF模式/
双参数云物理方案/
卫星模拟器/
敏感性试验
Abstract:In this study, strong precipitation generated by the landing of typhoon Fung-Wong in 2008 was simulated using WRF WDM6 double-moment cloud microphysics scheme. The model simulations were evaluated by statistical methods using cloud top brightness temperature (TBB) and precipitation radar reflectivity data from MTSAT-1R, TRMM satellite, and the Satellite Data Simulator Unit. To reduce the difference between the simulation results and satellite observations, sensitivity experiments were conducted in relation to autoconversion rate of cloud water to rain, ice nucleation, terminal velocity, and slopes of snow and graupel. The results show that the precipitation, strong convective cloud system, and convective columnar radar echo simulated by the WDM6 scheme are in agreement with observations, however, showing stronger results in some areas. The WDM6 scheme simulation produced more shallow convective clouds and underestimated the frequency of convective cloud systems. The radar echoes simulated by different cloud types are all strong, and the vertical distribution of the convective cloud radar echoes is close to observation. The experimental results show that modifying the production rate for the autoconversion of cloud water to rain in the WDM6 scheme effectively improves the simulation results. Simultaneously, it is found that the concentration of initial cloud droplets affects the production rate for the autoconversion of cloud water to rain and ultimately affects the simulation results of the cloud structure and radar reflectivity. A high concentration of initial cloud droplets will worsen the simulation result.
Key words:WRF model/
Double-moment microphysical parameterization/
Satellite Data Simulator Unit (SDSU)/
Sensitivity experiment
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