基于CORS网数据的河南“7·20”特大暴雨期间大气水汽分布特征分析

Analysis of Distribution Characteristics of Precipitable Water Vapor during the ″7·20″ Extremely Heavy Rainstorm in Henan Province Based on CORS Data

河南“7·20”特大暴雨导致了严重的城市内涝和多起地质灾害。大气水汽是发生极端降雨的主要驱动力之一,分析“7·20”特大暴雨期间大气水汽的时空变化,有助于提高对降雨-水汽区域性作用机制的认识。利用河南CORS网中8个GNSS测站的观测数据,反演了暴雨前后(7月17—24日)时间分辨率为5 min的PWV数据,在此基础上与基于ERA-5再分析数据通过积分求得的PWV值进行了对比,并结合实际降雨量分析了暴雨期间水汽的时空分布特征。结果表明:GNSS-PWV的偏差和均方根误差分别为0.4、2.3 mm;暴雨前3 d内PWV值呈现快速上升趋势,并在暴雨前3 h达到最大值,在7月22日后逐渐减少到正常范围;GNSS-PWV的变化趋势与实际降雨过程基本符合。研究结果可为基于GNSS观测数据的实时全天候气象预警工作提供一定的理论基础。

The ″7·20″ extremely heavy rainstorm in Henan Province caused serious urban waterlogging and several geological disasters.Precipitable water vapor(PWV) is one of the main drivers of extreme rainfall,and the analysis of the spatial and temporal variations of atmospheric water vapor during the ″7·20″ extremely heavy rainstorm can help to improve the understanding of the mechanism of rainfall and water vapor regional interaction.The PWV data with a temporal resolution of 5 min before and after the rainstorm from July 17 to July 24 were inverted using observations from eight GNSS stations in the Henan CORS network.On this basis,the integrated PWV values were compared with those of the ERA-5 reanalysis data,and the spatial and temporal distribution characteristics of water vapor during the rainstorm were analyzed in relation to the actual rainfall.The results are as follows.The deviation and root mean square error of GNSS-PWV are 0.4 and 2.3 mm,respectively.The PWV values showed a rapid increasing trend during the 3 days before the storm and reached the maximum value 3 hours before the storm,and gradually decreased to the normal range after July 22.The variation trend of GNSS-PWV is basically consistent with the actual rainfall process.The research results can provide a certain theoretical basis for real-time all-weather meteorological warning work based on GNSS observation data.