气象2024，Vol.50Issue(8)：917-928,12.DOI:10.7519/j.issn.1000-0526.2024.030801
广西初春双对流强降水带过程诊断分析
Diagnostic Analysis of a Process of Double-Convective Heavy Precipitation Bands in Guangxi in Early Spring
摘要
Abstract
Guangxi encountered a process of double-convective-bands from 20:00 BT 25 to 08:00 BT 26 March 2023.This process was significantly different from that of the double rain belts in the past,causing significant deviations in the subjective and objective forecasts.Based on multi-source observation data and ERA5 reanalysis data,the Rossby wave energy dispersion,moist potential vorticity and horizontal fronto-genic forcing in this process are analyzed.The results show that this process occurred under the back-ground of large-scale circulation adjustment.The two Rossby wave trains that originated from the polar vortex and the Black Sea in the mid-and high-latitude jointly promoted the gradual vertical rotation of the transversal trough in the northeast region,guiding the mid-and high-latitude cold air further southward.During this period,the south branch trough in the low latitude gradually moved eastward,providing the dynamic lifting above the cold cushion in Guangxi,and also promoting the convergence of cold and warm airs in the low troposphere in Guangxi.With the addition of cold air to south and the southerly winds ad-vancing northward under the inertial oscillation,the convergence of warm and cold airs in Guangxi was en-hanced.The enhancement of atmospheric moist baroclinicity led to the development of moist potential vor-ticity,resulting in conditional symmetric instability of stratification.The warm-moist air climbed from south to north reaching the conditional symmetric instability area near 700 hPa,and then combined with the positive vorticity advection in front of the upper-level trough to trigger elevated convection,resulting in the development of the north-branch convective band.Influenced by the special topography of Guangxi,the favorable configuration of the θse isoline and the flow formed a tensile deformation effect,leading to fro-ntogenic forcing,which triggered the initial convection in the south branch of Northeast Vietnam.The large θse latitudinal gradient and strong vertical wind shear in the low level of the central Beibu Gulf resul-ted in strong moist baroclinicity,which promoted the organization and development of the south-branch convective system when it passed through,and formed bow echo due to the mid-level dry air entrainment.In order to capture the key information of the occurrence and development of elevated convection after the north-branch front,it is necessary to focus on the numerical model in forecasting the mid-level trough and the thermo dynamic conditions above the cold air cushion.关键词
双对流带/双雨带/高架对流/条件对称不稳定/惯性振荡/锋生强迫Key words
double-convective-bands/double rain belts/elevated convection/conditional symmetric insta-bility/inertial oscillation/frontogenic forcing分类
大气科学引用本文复制引用
覃皓,邱滋,范娇,农孟松,赖珍权,翟舒楠,刘乐,刘晓梅,庞芳,周亦靖..广西初春双对流强降水带过程诊断分析[J].气象,2024,50(8):917-928,12.基金项目
广西自然科学基金项目(2023GXNSFBA026349、2022GXNSFBA035565)、广西重点研发计划项目(桂科AB22080101)和广西气象科研计划项目(桂气科2024M02)共同资助 （2023GXNSFBA026349、2022GXNSFBA035565）
