大气科学学报2025，Vol.48Issue(1)：77-92,16.DOI:10.13878/j.cnki.dqkxxb.20240418002
"海葵"台风残涡极端暴雨的对流组织特征及成因
Structure and organization of convection during extreme precipitation as-sociated with the remnant vortex of typhoon Haikui
摘要
Abstract
On September 7,extreme torrential rainstorms struckthe Greater Bay Area(GBA),including Hong Kong,Macau,and parts of Guangdong Province near the Peal River Estuary in South China.This event resulted in historical accumulated precipitation exceeding 800 mm within 24 hours in Hong Kong,causing severe social and economic losses.Operational numerical forecast models showed limited skill in predicting the intensity and location of this extreme rainfall.Using multi-source meteorological observations,this study analyzed the precipita-tion characteristics,convection initiation,organization,and underlying causes of the extreme precipitation through circulation diagnostics,thermodynamic analysis,and vorticity budgeting.The rainfall was primarily associated with remnant vortex of the decayed typhoon Haikui.Synoptic analysis revealed that the typhoon vortex decayed rapidly after landfall in Fujian Province,South China.Due to weak mid-level environmental steering,the westward-moving remnant vortex stagnated over the GBA,north of the Pearl River Estuary,from the morning of September 7 until early evening on September 8.On the night of September 7,an enhanced easterly boundary layer jet com-bined with southwesterly monsoon airflowfrom the South China Sea,forming an intensified southeast jets tronger than predicted in numerical models.This southeast jet injected large amounts of moist,unstable air into the remnant vortex circulation over the GBA,triggering excessive precipitation.Significant low-level convergence and frontogenesis provided favorable conditions for mesoscale lifting.Late on September 7,a mesoscale jet pulse with boundary-layer wind speeds exceeding 20 m/s was detected by a wind profiler in Shenzhen.The mesoscale con-vergence and frontogenesis near the jet exit intensified convection initiation and precipitation.Revival of the rem-nant vortex in the boundary layer was closely linked to latent heat gradients below the mid-level maximum heat-ing center.Weather radar observations revealed that from 14:00 BST on September 7,convection and precipitation intensified,forming a quasi-linear convective belt composed of rapidly growing discrete convective cells along the west shore of the GBA.A secondary,weaker convective line formed along the east shore,organized along the boundary between shallow easterly airflow and southwesterly monsoon winds.These two linear mesoscale convec-tive systems(MCS)merged near Hong Kong's southern coast,persisting for over 12 hours.A series of north-ward-moving convective cells repeatedly passed over Hong Kong and Shenzhen along similar tracks,inducing lo-calized extreme rainfall.A maximum rainfall intensity of 158 mm/h was recorded in Hong Kong.After 14:00 BST on September 8,the remnant vortex of Haikui gradually moved westward toward Guangxi Province,leading to weakened rainfall in the GBA.Observation of raindrop size distributions showed that the precipitation had charac-teristics typical of maritime convection,with significant increases in raindrop size during periods of enhanced rain-fall.This increased precipitation efficiency in the deep moist layer.The convection exhibited a low echo centroid structure withstorm tops exceeding 8 km,facilitating rapid growth of raindrops through coalescence during descent.Embedded β-and γ-mesoscale vortices within the linear MCS contributed to the extreme rainfall intensity.These vortices,identified using Doppler radar observations in Shenzhen,warrant further investigations.关键词
台风残余环流/极端暴雨/对流/低空急流Key words
typhoon remnant/extreme precipitation/convection/low-level jet引用本文复制引用
陈涛,李嘉睿,许先煌,谌芸.."海葵"台风残涡极端暴雨的对流组织特征及成因[J].大气科学学报,2025,48(1):77-92,16.基金项目
国家自然科学基金气象联合基金重点支持项目(U2342226) （U2342226）
灾害天气国家重点实验室开放课题(2021LASW-A16) （2021LASW-A16）
风云卫星应用先行计划项目(FY-APP-2022.0101 （）
FY-APP-ZX-2023.01) （）
