| China belongs to the Asian monsoon climate zone,especially in East and South China,which often brings many natural disasters due to the monsoon.In recent years,rainstorm disasters have occurred frequently,and more and more scholars have carried out research on rainstorm and other severe thunderstorm.The geographical position of Henan Province is in the inland area of central China.It often suffers from natural disasters such as rainstorm and drought in summer.The “21·7” Henan Province extremely heavy rainfall was very rare,and the hourly rainfall intensity exceeds historical extreme value(201.9mm),which has brought huge economic losses to Henan Province.In this paper,the NCEP/NCAR reanalysis data,Himawari-8 data,T-log P diagram(T-log P)method,wind vector potential temperature plot(v-3?)method and dual-polarization radar data are used to analyze the case of the “21·7” Henan Province extremely heavy rainfall from July17 to 23,2021.The main conclusions are as follows:(1)By analyzing the weather situation and local atmospheric vertical structure,it is found that the “21·7” Henan Province extremely heavy rainfall is an extremely rare torrential rain process formed by the topographic uplift of Funiu Mountain and Taihang Mountain under the climate background of the abnormal lifting of subtropical high and the strong summer monsoon in the same period.Using the cloud image of Himawari-8 satellite to track the movement process of Typhoon In-Fa,combined with the position of subtropical high,the water vapor source model of the torrential rain in Henan is established.Besides,from the atmospheric thermal and dynamic structure,pay attention to the physical information of the troposphere,and provide reference information for the prediction and early warning of severe rainstorm in combination with water vapor conditions.From 08:00 on the 20 th,on the T-log P diagram of Zhengzhou station,the three lines of state curve,dew point profile and temperature profile almost coincide.From 925 h Pa to 300 h Pa,there were southeast wind and southerly wind,so the water vapor was very sufficient;the V-3? plot showed a multi-layer strong cooling structure,ultra-low temperature at the tropopause,cold stratus clouds in the middle and lower layers,and the special atmospheric structure made the rainfall in Zhengzhou break through the historical extreme value from 16:00 to 17:00 on the 20 th.(2)Using the data obtained from the dual-polarization radar of Zhengzhou station and Luoyang station,the evolution of the dual polarization radar echo is analyzed from 16:00 to17:00 on July 20,2021(i.e.the hourly maximum rain intensity period),and the intensity information of the rainstorm is obtained in combination with the velocity figure,vertical profile and velocity profile;Through comprehensive analysis of the causes of the torrential rain,it is found that there was a mesocyclone from 16:00 to 17:00,and combined with the circulation background field,there was a three-dimensional spiral vortex structure over Zhengzhou,revealing the reasons for the historical extreme value of the torrential rain in Henan and the long duration of the torrential rain,that is,the one hour continuous existence of the mesocyclone echo corresponds to the extreme value of the torrential rain from 16:00 to 17:00 on July 20.To deepen the understanding of the vertical and dynamic structure of the internal atmosphere in the process of severe rainstorm,the three-dimensional vortex model of rainstorm is constructed.(3)As both rainstorm weather and tornado weather belong to strong thunderstorm,they have many similarities and differences in weather scale,atmospheric structure and dual polarization radar echo characteristics.Therefore,it is of great significance to compare the case of extremely heavy rainfall in Henan with the case of tornado weather to the research of disastrous weather. |
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