Environmental Fields and Radar Echo Characteristics of Pre-Typhoon Severe Convection in the Guangdong-Hong Kong-Macao Greater Bay Area
GUO Ruiling
LU Jieying
CHAO Jinghua
YU Rui
YU Xiaojian
HE Jincheng
Abstract：To investigate the environmental background of pre-typhoon severe convective weather,this study analyzes radar echo characteristics,circulation patterns,and selected physical parameters of pre-ty-phoon severe convection events in the Guangdong-Hong Kong-Macao Greater Bay Area from 2007 to 2022,using MICAPS upper-air and surface observations,radar reflectivity,typhoon tracks,and NCEP FNL reanal-ysis data.The results show that pre-typhoon severe convection occurs most frequently from July to August,particularly from noon to evening.These events mainly develop at the edge or within the circulation of the subtropical high,with low-level southerly flow or northerly flow from the typhoon periphery,and the surface is often located near a trough or in a quasi-uniform pressure field.Nearly 30％of pre-typhoon squall lines have a maximum 40 dBZ echo length of 200-250 km.Over 90％of cases exhibit maximum echo intensities between 55-65 dBZ,with 78％of non-squall line events falling within this range.Radar echoes most fre-quently move northwestward,with pre-typhoon squall lines averaging a speed of 32 km·h-1and a mean li-fespan of about 5.1 hours.Considering seasonal variations,t850-500,t925-700,and the Most Unstable Lifted Index(MULI)show certain predictive indications for pre-typhoon severe convection events from September to October.This study enhances the understanding of pre-typhoon severe convection mechanisms in the Greater Bay Area,providing valuable insights for early warning systems and improving forecasting accuracy of high-impact weather events under typhoon influence.
Keywords：synopticspre-typhoon severe convectionsquall linenon-squall lineradar echoGuangdong-Hong Kong-Macao Greater Bay Area
Publication Date：2025-08-20
Online Publishing Date：2025-09-15(First online date of this platform, not the publication date of the document)
Pages：6( 12-17 )