西南山区5-8月产生突发性暴雨事件的中尺度对流系统的时空分布特征  

Temporal and spatial characteristics of mesoscale convective systems associated with abrupt heavy rainfall events over Southwest China during May—August

作　　者：王婧羽 崔春光[1] 陈杨瑞雪 王晓芳[1] WANG Jingyu;CUI Chunguang;CHEN Yangruixue;WANG Xiaofang(Hubei Key Laboratory for Heavy Rain Monitoring and Warning Research,Institute of Heavy Rain,China Meteorological Administration,Wuhan 430205,China;School of Atmospheric Sciences,Chengdu University of Information Technology,Chengdu 610225,China)

机构地区：[1]中国气象局武汉暴雨研究所/暴雨监测预警湖北省重点实验室,武汉430205 [2]成都信息工程大学大气科学学院,成都610225

出　　处：《气象学报》2022年第1期21-38,共18页Acta Meteorologica Sinica

基　　金：国家重点研发计划专项(2018YFC1507202);国家自然科学基金项目(41975058、41705019);湖北省气象局科技发展基金项目(2020Y04)。

摘　　要：利用逐时的风云静止卫星黑体亮温(TBB)资料和国家级地面站降水观测资料,根据中尺度对流系统(MCS)的逐时云顶覆盖范围是否包含突发性暴雨事件,识别出2010-2018年5-8月与中国西南山区突发性暴雨事件相关的中尺度对流系统(AHR-MCS),并得到其统计特征。结果表明,该地区AHR-MCS在7月出现最频繁,存在四川盆地(SR-A)、湖南西部(SR-B)、广西北部(SR-C)和贵州西南部(SR-D)4个不连续的频发区。经向扰动环流、整层水汽通量的异常辐合、低层更强的暖湿气流及其引起的偏强对流层低层风垂直切变(6-8月)是AHR-MCS出现和维持的有利条件。AHR-MCS是西南山区内生命期更长的那部分中尺度对流系统,主要移动方向偏东,但位置偏西(东)的SR-A、SR-D(SR-B、SR-C)频发区域内向东偏南(东偏北)方向移动得更多。成熟时,SR-A的发展高度更低,面积更小,SR-B和SR-C的云顶面积更大而SR-D则云顶高度更高。AHR-MCS的日变化呈现明显的单峰结构,20-23时(北京时)达到峰值,其中生命期越长的生成(成熟)峰值出现时间越晚。对于不同频发区,SRA和SR-D也是单峰结构,但由于受大地形的热力影响前者生成(成熟)峰值明显晚于后者6(8) h;其余两个区域则呈现多峰结构。AHR-MCS对应的最大小时降水更易出现在发展阶段,与最低TBB出现的时间对应关系更好,早于成熟时;位置则多分布在相对于对流云团形心的第Ⅰ、Ⅲ象限;不仅容易出现在TBB低值区(低于-51℃)还常出现在TBB的梯度大值区(超过0.4℃/km),且两者占比相当。Based on temperature of brightness blackbody(TBB)data from FY-2 E(2010-2014)and FY-2 G(2015-2018)and 468 rain gauges,temporal and spatial characteristics of the mesoscale convective systems associated with abrupt heavy rainfall events(AHR-MCS)over southwest China(SWC)in May-August of 2010-2018 are investigated according to whether the hourly cloud tops of mesoscale convective systems(MCS)cover the gauged-based abrupt heavy rainfall.AHR-MCSs appear most frequently in July with high frequencies over 4 discrete subregions located in Sichuan basin(SR-A),western Hunan(SR-B),northern Guangxi(SR-C)and southwestern Guangxi(SR-D).Abnormal meridional circulations,large divergence anomalies of vertically integrated water vapor flux,high moist static energy anomalies and strong wind shear(June-August)between surface and 700 hPa(especially in June-August)are favorable for AHR-MCSs.AHR-MCSs are the MCSs that have longer lifespan over SWC.They mainly move eastward,but those located in the western(eastern)part of SWC over SR-A and SR-D(SR-B and SR-C)more frequently move southeastward(northeastward).When they are mature,the MCSs in SR-A usually have smaller cloud areas and lower cloud tops,while those in SR-B and SR-C have larger areas and those in SR-D have higher cloud tops.AHR-MCSs appear most frequently during20:00-23:00 BT with diurnal unimodal structure,and the peak occurs later as the lifespan is longer.There is only one peak over both SR-A and SR-D,but the peak occurrence time of the former is 6-8 h later than that of the latter.Besides,multi-peak structure of AHR-MCS frequency appears over SR-B and SR-C.The maximum hourly precipitation mostly appears during the development stage of the AHR-MCS,and often corresponds to the time when the minimum TBB shows up,earlier than the mature time.Gauges within maximum hourly precipitation are often located in theⅠandⅢquadrants of clouds when the minimum TBB occurs.The maximum hourly precipitation not only frequently appears in the cloud areas of lower TBB(<-51℃),but also appea

关 键 词：西南山区 突发性暴雨事件 中尺度对流系统 统计特征 

分 类 号：P458.121.1[天文地球—大气科学及气象学]