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气象:2023,49(3):304-317
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能量转化视角下一次引发冬季区域强对流的南支槽研究
覃皓,伍丽泉,石怡宁,刘乐
(广西壮族自治区气象台,南宁 530022;广西壮族自治区气象灾害防御技术中心,南宁 530022;广西壮族自治区气候中心,南宁 530022;中国气象局地球系统数值预报中心,北京 100081; 中国气象科学研究院灾害天气国家重点实验室,北京 100081)
Study on the Southern Branch Trough Inducing a Winter Regional Severe Convection from the Perspective of Energy Conversion
QIN Hao,WU Liquan,SHI Yining,LIU Le
(Guangxi Meteorological Observatory, Nanning 530022;Guangxi Meteorological Disaster Prevention Technology Center, Nanning 530022; Guangxi Climate Center, Nanning 530022;Center for Earth System Modeling and Prediction of CMA, Beijing 100081; State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081)
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投稿时间:2022-02-25    修订日期:2022-08-01
中文摘要: 2020年1月24—25日广西出现一次罕见区域性强对流,过程伴随近20年最大范围冰雹天气。南支槽异常发展东移是此次过程的扰动背景,提供了必要的热动力及水汽条件。基于波作用通量及多尺度能量诊断方法,利用常规观测资料、风云卫星资料、NCEP/NCAR以及ERA5再分析资料,从能量转化角度对此次引发区域强对流的南支槽过程进行研究。结果表明:整个过程中纬度和副热带西风急流均较历史同期偏强,有利于上游扰动向下游传播。欧亚大陆上空存在南北两支活跃Rossby波列。源自地中海一带的南支副热带西风急流Rossby波列对南支槽起到主要调控作用,Rossby波能量沿急流频散并在南支槽区辐合,促进了南支槽发展东移。源自北大西洋阻塞高压内部的北支Rossby波列则起到协同作用,促进了乌拉尔山冷槽发展及其与中东槽合并,从而增强了南支波列向下游的传播,进一步增强南支槽;天气尺度有效位能向天气尺度动能的转换以及由背景场向天气尺度的动能输送是南支槽天气尺度扰动发展的主要贡献项。动能的平流输送将获得的天气尺度动能在空间上再分配,维持南支槽稳定发展东移。在此背景下,天气尺度向对流尺度的降尺度动能串级是区域强对流最主要能量源,同时对流尺度有效位能向动能的稳定转换促进了中低对流层的对流扰动发生发展。
Abstract:A rare regional severe convection process of Guangxi occurred in 24-25 January 2020, which was accompanied by the maximal range hail process since 2000. The abnormal development and eastward of the southern branch trough (SBT) were the disturbance backgrounds that provided necessary thermal, dynamic and water vapor conditions. Based on conventional observation data, FY-2G satellite data, NCEP/NCAR and ERA5 reanalysis data, the SBT inducing the regional severe convection process is analyzed from the perspective of energy conversion. The results show that the mid-latitude and subtropical westerly jets were stronger than those in the same peried in history during the whole process, which were conducive to the upstream disturbance spreading. There were two active Rossby wave trains over the northern and southern Eurasia respectively. The southern subtropical westerly jet Rossby wave originated from the Mediterranean Sea played a major role in regulating the SBT. The Rossby wave energy dispersed along the jet stream and converged in SBT region, promoting the development and eastward of SBT. The northern one originated from the North Atlantic blocking played a synergistic role, promoting the development of the Urals cold trough and its merger with the Middle East trough, thereby enhancing the propagation of the southern one and further enhancing the SBT. The conversion from synoptic-scale available potential energy and the transport of kinetic energy from background field to synoptic-scale were the main contributions of synoptic-scale disturbance of SBT. The advection transport of kinetic energy redistributed the obtained synoptic-scale kinetic energy in space and thus maintained the stable development of SBT and moving eastward. Under the above background, the downscaled kinetic energy cascade from synoptic-scale to convective scale became the main energy source of regional severe convective, and the stable conversion of convective scale available potential energy to kinetic energy promoted the occurrence and development of the convective disturbances in the middle and low troposphere.
文章编号:     中图分类号:P458    文献标志码:
基金项目:广西重点研发计划(桂科AB21075008)、广西气象科研计划项目(桂气科2022QN08、桂气科2021QN03)和广西壮族自治区气象局短时临近天气预报技术创新团队项目共同资助
引用文本:
覃皓,伍丽泉,石怡宁,刘乐,2023.能量转化视角下一次引发冬季区域强对流的南支槽研究[J].气象,49(3):304-317.
QIN Hao,WU Liquan,SHI Yining,LIU Le,2023.Study on the Southern Branch Trough Inducing a Winter Regional Severe Convection from the Perspective of Energy Conversion[J].Meteor Mon,49(3):304-317.