同化MWHS-2/FY-3C资料对一次西南涡暴雨数值模拟的影响研究

Study of the Impact of the Assimilation of FY3C Microwave Humidity Sensor-2 Data on a Case of the Numerical Simulation of the Southwest China Vortex-induced Rainstorm

利用WRF模式及WRFDA同化系统,循环同化风云三号微波湿度计资料(MWHS-2),对2019年6月4日四川西南涡暴雨天气过程进行数值模拟试验。结果表明:WRF模式成功预报出本次暴雨天气过程,同化MWHS-2观测资料对模式初始场盆地中东部的相对湿度有明显调整,较控制试验对盆地降水的模拟结果更接近于实况,不仅改善了700hPa低涡模拟路径与实况路径的差距,也改善了模拟结果中850hPa西南涡在盆地东部打转的虚假活动路线。整个过程中水汽辐合区与强降水区有很好的对应关系,强降水主要出现在700hPa低涡东南侧偏南气流气旋性曲率最大值区与850hPa低涡切变南侧的重叠位置。

Based on the WRF model and WRFDA assimilation system,the numerical simulation of the Southwest China Vortex(SWCV)-induced rainstorm process in Sichuan Basin on June 4th,2019 was carried out by assimilating FY3C Microwave Humidity Sensor-2(MWHS-2).The results show that the WRF model successfully predicts this heavy rainstorm,and the relative humidity(RH)of the mid-east Sichuan Basin in the model initial field is largely adjusted by assimilating MWHS-2 data.The assimilated precipitation in the Basin is closer to the ground truth than the unassimilated simulation.It not only improved the gap between the simulation path of 700hPa vortex and the actual path,but also improved the false activity path of 850hPa southwest vortex in the eastern basin in the simulation results.In the whole process,the water vapor convergence zones correspond well with the heavy rainfall zones,which mainly occur near the area where the southeastern flank of the 700hPa vortex’s cyclonic curvature reaching maximum overlaps the southern flank of the 850hPa vortex’s shearing.