广西初春双对流强降水带过程诊断分析

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国家科技期刊平台
NETL
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中文摘要：2023年3月25日20:00至26日08:00，广西出现一次双对流强降水带过程，与以往双雨带存在显著差异，主、客观预报均出现明显偏差。利用多源实况以及ERA5再分析资料，对此次过程进行了 Rossby波能量频散、湿位涡及水平锋生强迫等诊断分析。结果表明:该过程发生于大尺度环流调整背景下，中高纬地区源自极涡以及黑海的两支Rossby波列共同促进了东北地区的横槽在东移过程中逐渐转竖，引导冷空气补充南下。低纬地区南支槽在此期间逐渐东移，为广西地区冷垫之上的气层抬升提供动力条件，同时也促进低层冷暖空气在广西交汇。随着冷空气补充南下、惯性振荡促使偏南风向北推进，冷暖空气在广西一带交汇增强，大气湿斜压性增强使得湿位涡发展，导致出现条件对称不稳定层结。暖湿空气自南向北倾斜爬升至700 hPa附近条件对称不稳定区后与高空槽前正涡度平流相配合触发高架对流，使得北支对流带发展。冷空气深入南下后受广西特殊地形影响，等θse线与流场的有利配置形成拉伸变形效应导致锋生强迫，使得越南东北部南支初始对流触发。北部湾中部低层较大θse纬向梯度以及强垂直风切变造成较强湿斜压性，促进南支对流系统途经时组织化发展，并由于中层干空气夹卷形成弓形回波。预报中需重点关注数值模式对中层低槽的预报以及冷垫上的热力条件，以捕捉北支锋后高架对流发生发展的关键信息。

外文标题：Diagnostic Analysis of a Process of Double-Convective Heavy Precipitation Bands in Guangxi in Early Spring

外文摘要：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.

外文关键词：

double-convective-bands/double rain beltselevated convectionconditional symmetric insta-bilityinertial oscillationfrontogenic forcing

作者：

覃皓、范娇、农孟松、赖珍权、翟舒楠、刘乐、刘晓梅、庞芳、周亦靖、邱滋

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作者单位：

广西壮族自治区气象台,南宁 530022

南宁市气象局,南宁 530029

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

基金：

广西自然科学基金项目广西自然科学基金项目广西重点研发计划项目广西气象科研计划项目

项目编号：

2023GXNSFBA0263492022GXNSFBA035565桂科AB22080101桂气科2024M02

出版年：

2024

DOI：

10.7519/j.issn.1000-0526.2024.030801

气象

国家气象中心

气象

CSTPCD北大核心

影响因子：2.337

ISSN：1000-0526

年,卷(期)：2024.50(8)