DIAGNOSTIC ANALYSIS OF TWO TORRENTIAL RAINFALL EVENTS IN 2020 IN SHENZHEN-SHANWEI SPECIAL COOPERATION ZONE

LIU Jiajing; LI Yongze; LIN Peixian; CHEN Yinlan; LI Tianran; WU Zhifang

doi:10.16032/j.issn.1004-4965.2023.062

Abstract：Using the ERA5 reanalysis data,observational data from automated weather stations,and local radar data,this paper presents a comparative study to analyze the rainfall,weather patterns,physical parameters,and radar echo characteristics during two extreme torrential rainfall events on May 20-22,2020(Process 1)and on June 6-8,2020(Process 2)in the Shenzhen-Shanwei Special Cooperation Zone(SSCZ).The results show that both of the two events occurred under the background of favorable large-scale circulation,and low-level jet(LLJ)streams provided sufficient water vapor.Meanwhile,the transport of low-level warm and humid airflow kept the low level of the rainstorm area under the control of high energy and high humidity for a long time,and the strong convergent upward motion provided favorable dynamic conditions.A surface convergence line was formed under the influence of a warm and moist airflow from the ocean and a southward cold airflow along the Lianhua Mountain.The difference was that the low-level wind speed in the rainfall area was stronger and the strengthening was more obvious,and the intensity of the mesoscale kinetic energy front was stronger in Process 1.In Process 2,the large value of water vapor flux was more northerly,and the unstable atmospheric stratification in the rainfall area was maintained for a longer period of time.The height range of the large value area of vertical motion was wider.The radar echo of Process 1 was a strong mono echo moving northward to the surface convergence line of the SSCZ.Subsequently,it developed rapidly and moved less,and was accompanied by a meso-γ-scale vortex.In Process 2,the radar echo was a linear strong echo that was triggered continuously near the long-maintained surface convergence line and thus the"train effect"was developed.