Analysis of Typhoon Precipitation Distribution and Circulation Characteristics in Jieyang City Based on Refined Observations

Lin Qiaomei; Chen Yuqiang; Lu Wei; Xia Yun; Chen Yuzhuang

doi:10.16765/j.cnki.1673-7148.2024.06.006

Abstract：Based on the tropical cyclones that landed in Guangdong from 2013 to 2022(collectively re-ferred to as typhoons,the same below;including one landing in Hong Kong),precipitation observation data from 85 meteorological observation stations in Jieyang City during the typhoons'impact periods,the European Centre for Medium Range Weather Forecasts(ECMWF)ERA5 0.25° ×0.25° circulation data,as well as the statistical analysis and cluster analysis methods,this paper analyzes the spatial distribution characteristics and circulation characteristics of the typhoon-caused rainfall in Jieyang City.The results show that typhoons that landed in Guangdong from 2013 to 2022 caused an average areal rainfall of 245.6 mm per year in Jieyang City,with a maximum of 455.2 mm in 2018 over the 10-year period.The monthly variation of precipitation shows a unimodal distribution,with the main rainfall peak seen in August and the average areal rainfall of 100.5 mm.Different landing paths resulted in different distribution characteristics of rainfall in Jieyang City.The typhoons that landed in the east path had the maximum average areal rainfall,followed by the average areal rainfall of typhoon landing in the west path,and the average areal rainfall was the lowest when typhoons landed in the middle path.The corresponding average areal rainfall amounts in the three paths were 90.3 mm,76.2 mm and 58.3 mm,respectively.When typhoon landed in the west path the hourly rainfall(92.2 mm)was the most,the second most hourly rainfall(89.6 mm)was with the landfall typhoon in the east path,and the least hourly rainfall(64.7 mm)was found in case typhoons landed in the middle path.Typhoons that landed on different paths had different locations of heavy precipitation centers(areal rainfall＞100 mm)in Jieyang City.As the typhoon landing path moved westward,the heaviest precipitation centers on the east path appeared in the area from Tangkeng Reservoir of Xiajiashan Town in the southeast of Puning City to Helin Town in the northeast of Huilai County;the heaviest precipitation centers in the middle path appeared in areas of Wujingfu Town and Wuyun Town of Jiexi County and Houxi Town of Puning City;and the heaviest precipi-tation centers in the west path appeared in areas of Junbu Town of Puning City and Hepo Town of Jiexi County.All of these heaviest rainfall centers were located on the windward slopes of mountain ranges.The circulation characteristics of typhoons with different landfall paths were different.For typhoons that landed in the east path,Jieyang City was located in the circulation field near the center of the typhoon,and the precipitation was mainly from the typhoon itself;the typhoons that landed in the middle path were mainly characterized by the rainfall from the peripheral circulation of the typhoon and unstable precipitation on the southwest side of the subtropical high;the typhoons that landed in the west path were located near Jieyang City at a cyclonic bend where the southerly airflow turned into the southeasterly airflow,which was more conducive to the convergence of water vapor.Overall,the precipitation of the east path typhoons＞that of the west path typhoons＞that of the middle path typhoons in Jieyang City.With typhoons of the west path and the middle path,Jieyang City was affected by their peripheral circulations.The amount of precipitation did not correspond well with the dis-tance of the typhoon landing point,mainly depending on the circulation situation.