Spatio-Temporal Distribution of Guangdong Tornadoes and Characteristics of Radar Echoes of Parent Storms
Based on tornado data from the China Meteorological Disaster Encyclopedia(Guangdong Vol-ume)(1959-2000),Guangdong Disaster Prevention and Mitigation Yearbook(2002-2022)and record of on-site disaster investigation of tornadoes in recent years,conventional observations and ERA5 high-resolution reanalysis data,as well as the data from Guangdong Doppler weather radar(2006-2022),we analyze the spatio-temporal distribution and weather background of tornadoes in Guangdong from 1961 to 2022,as well as the morphology of tornado convective storms since 2006.The results are as follows.In the past 62 years,Guangdong has recorded a total of 225 tornadoes.Since 2006 when multiple sources of ob-servation data are relatively complete,about 6 tornadoes have occurred annually.About 50％of tornadoes occurred in the background of tropical cyclone weather,followed by 40％of tornadoes in the westerly weather system,and about 10％of tornadoes were tropical disturbance tornadoes.However,the number of tornadoes fluctuated greatly year by year,up to 17 in 2008.In some years,there was only one tornado or no tornadoes recorded.In general,tornadoes in Guangdong mainly occur from April to September.From April to June,they are mainly westerly tornadoes and from July to September,mainly tropical cy-clone tornadoes and tropical disturbance tornadoes.About 85％of tornadoes occur between 06:00-20:00 BT,with the highest occurrence between 14:00-18:00 BT,accounting for about 40％.Tornadoes occur most frequently in the Pearl River Delta,Leizhou Peninsula and Chaoshan Plain.There are few tornadoes in the northern mountainous areas.Foshan,Zhanjiang and Guangzhou are the cities with the highest fre-quency of tornadoes.About 54％of convective systems generating tornadoes in Guangdong are banded convective systems,which are tropical cyclone tornado parent storms and tropical disturbance tornado par-ent storms.The storm structures exhibit low centroid characteristics.About 36％are multi-cell storm sys-tems,most of which are westerly tornado parent storms.Different from the tornadoes in the United States that tend to occur in discrete cells and quasi-linear convective systems,the relative frequencies of discrete convection cell and quasi-linear convective systems generating tornadoes in Guangdong are very low,both about 5％.They are the parent storms of the tornadoes in the westerly and their storm structures often show the characteristics of high centroid.More than 90％of tornado mesoscale parent storms have low-level mesocyclones,but only about 47％of the tornado parent storms are accompanied by low-level tornado vortex signature(TVS).Strong tornadoes are typically characterized by low-level mesocyclones with rota-tional speeds exceeding 20 m·s-1 and TVS velocity differences exceeding 40 m·s-1.
万方数据
维普
