1971—2020年辽宁龙卷的气候特征及环境条件分析  

Climatology and Environmental Feaures of Tornadoes in Liaoning Province During 1971-2020

作　　者：袁潮 杨文艳 李得勤[1] 杨磊 王式功[5] YUAN Chao;YANG Wenyan;LI Deqin;YANG Lei;WANG Shigong(Shenyang Institute of Atmospheric Environment,CMA,Shenyang 110166;China Meteorological Administration Tornado Key Laboratory,Guangdong,Foshan 528315;Panjin Meteorological Office of Liaoning Province,Panjin 124010;Liaoning Meteorological Disaster Warning Center,Shenyang 110166;School of Atmospheric Sciences,Chengdu University of Information and Technology,Chengdu 610225)

机构地区：[1]中国气象局沈阳大气环境研究所,沈阳110166 [2]中国气象局龙卷风重点开放实验室,广东佛山528315 [3]辽宁省盘锦市气象局,盘锦124010 [4]辽宁省气象灾害监测预警中心,沈阳110166 [5]成都信息工程大学大气科学学院,成都610225

出　　处：《气象》2023年第11期1285-1298,共14页Meteorological Monthly

基　　金：国家自然科学基金青年项目(42305013);中国气象局气象能力提升联合研究专项(23NLTSQ002);中国气象局创新发展专项(CXFZ2022J059、2022J003);中国气象局预报员专项(CMAYBY2020-026);东北冷涡研究重点开放实验室开放基金(2022SYIAEKFMS05)共同资助。

摘　　要：为了解辽宁龙卷气候特征,基于《中国气象灾害大典》《中国气象灾害年鉴》和其他相关资料,根据“改进藤田分级”龙卷级别分类标准,对1971—2020年辽宁龙卷进行强度分类和时空分布特征统计,并对比我国辽宁与美国龙卷高发区环境背景差异,分析辽宁龙卷典型的环流形势、物理量特征。得到以下主要结论:1971—2020年辽宁地区共记录到97个龙卷日发生龙卷105次,年均为2.1次,年平均龙卷生成密度为1.4×10^(-5)个·km^(-2),约为美国的1/10。EF2及以上级别强龙卷共记录到17次,年均出现0.3次。95%的龙卷出现在5—9月,67%出现在14—19时。EF2及以上级别强龙卷主要分布在辽宁中部以西地区,东南沿海地区多为弱龙卷,辽宁西北部龙卷季明显早于东南部。对流有效位能和中低层风切变随季节呈反相位变化,两者的合适配置是龙卷等强对流天气产生的前提条件。低层风暴相对螺旋度偏小是我国辽宁较美国龙卷高发区龙卷密度明显偏小的主要原因。辽宁87%的龙卷与冷涡相关,分为低层锋生主导的冷涡底部短波槽和冷涡前部型(65%)、中高空干冷气流主导的冷涡后部型(12%)以及强热力不稳定条件下中尺度近风暴环境主导的冷涡主体型(6%)。辽宁龙卷高发区典型环境条件具有以下特征:中层影响系统为冷涡,地面对应锋面气旋;龙卷常出现于低层风暴相对螺旋度中心偏西北象限,对流有效位能梯度大值区内,对应地面冷锋和干线的东侧、温度脊顶部。A climatology,which includes interannual variability,annual and diurnal cycles,intensities according to the“Enhanced Fujita Scale”,geographic distribution,and environmental conditions derived from reanalysis data,is developed in this study for the tornadoes in Liaoning Province during 1971-2020 in order to understand the climatic characteristics of tornado.The tornado reports are obtained from the Chinese Meteorological Disaster Dictionary,Chinese Meteorological Disaster Yearbook and other associated data.The differences in environmental background between Liaoning Province in China and the tornado-prone areas in United States are compared,and the typical circulation conditions and atmospheric characteristics of Liaoning tornadoes are analyzed.The major findings are as follows.Over the 50 years(1971-2020),there were 105 tornadoes recorded(including 17 EF2 or stronger tornadoes)in 97 tornadic days in Liaoning Province,which suggests that Liaoning has 2.1 tornadoes per year with the annual generation density to be 1.4×10^(-5) km^(-2),approximately equal to 1/10 tornadoes in the United States.A total of 17 EF2 or stronger tornadoes are recorded,with an average annual occurrence of 0.3.The tornadoes occur mostly(95%)from May through September,and 67%of tornado genesis are between 14:00 BT and 19:00 BT.Significant tornadoes(EF2/EF3/EF4)mainly occur in the central and western part of Liao-ning,while weak tornadoes(EF0/EF1)happen more in the coastal region of the southeastern Liaoning.The tornadic season in the northwest of Liaoning is much earlier than in the southeast.CAPE and mid-level wind shear often change in opposite phases with seasons,and the appropriate configuration of the two is the prerequisite for the occurrence of tornadoes and other convective weather.Additionally,the lower low-level the storm relative helicity(SRH)is the major cause for the apparently lower tornado density in Liaoning relative to the United States.About 87%of tornadoes are related to the cold vortices,which can be mainly divided in

关 键 词：龙卷 时空分布 环境条件 冷涡 风暴相对螺旋度 

分 类 号：P445[天文地球—大气科学及气象学] P463