江淮梅雨期不同类型暴雨过程锋生特征分析  

Analysis of the frontogenesis characteristics of different types of rainstorms in the Jianghuai Meiyu period

作　　者：金小霞[1] 刘梅[1,2] 李杨 王磊[1] 李驰钦[1] 陈蔚 JIN Xiaoxia;LIU Mei;LI Yang;WANG Lei;LI Chiqin;CHEN Wei(Jiangsu Meteorological Observatory,Nanjing 210008,China;Key Laboratory of Transportation Meteorology,China Meteorological Administration,Nanjing 210009,China)

机构地区：[1]江苏省气象台,江苏南京210008 [2]中国气象局交通气象重点开放实验室,江苏南京210009

出　　处：《大气科学学报》2023年第4期600-614,共15页Transactions of Atmospheric Sciences

基　　金：国家重点研发计划项目(2021YFC3000905);长江流域气象开放基金项目(CJLY2022Y02);江苏省气象局重点项目(KZ202101)。

摘　　要：利用ERA5再分析资料和江苏省自动站降水量资料,根据运动学锋生原理,分析了2020年江淮梅雨期锋生特征和两类不同性质暴雨锋生的差异,揭示了不同层次锋生与降水的对应关系。研究结果表明:1)2020年梅雨期锋生特征显著,强降水与中低层锋生有较好对应关系,其中形变项占主要贡献,散度项次之,倾斜项最弱。强降水时段总锋生、散度和形变锋生作用叠加。2)江苏地区自北向南锋生特征有差异,强度逐渐减弱,锋生发展高度逐渐降低。不同类型降水锋生特征不同,对流性降水锋生范围偏大、发展层次高、锋生中心偏强,总锋生和各分解项叠加作用显著,稳定性降水锋生特征反之。3)典型过程对流降水“6.28”和稳定性降水“7.11”对比表明:锋区位置相近,锋生作用均出现在江淮切变线附近,锋区、切变线和θse密集带三者对应较好。降水落区有差异,对流性降水过程中,由于干冷空气的显著南压,使得主要降水发生在锋面南侧暖区,与多个次锋生中心相对应;稳定性降水过程中冷暖空气势力相当,降水主要集中在主锋区附近,触发机制和降水性质不同导致降水分布差异。4)两次过程垂直锋区由低到高均有向北倾斜的特征,“6.28”过程锋区南侧有显著暖湿气流输送,锋区内为强烈上升运动,低层辐合高层辐散的环流场使得锋区维持。“7.11”过程垂直上升运动高度偏低,高空没有显著辐散场,对流性较弱。对两类降水垂直锋区的合成分析表明,对流性降水的低层锋生明显强于稳定性降水,由低层锋区造成的抬升触发作用对强降水形成更加有利,同时垂直风场的合成中上升运动也更加强烈。两类降水中,中低层散度和形变锋生由低到高均为先增大后减小,强降水主要由700 hPa以下锋生增强导致,中高层大气基本为锋消作用。This study analyzes the frontogenesis characteristics of rainstorms during the Meiyu period in 2020 using ERA5 reanalysis data and the precipitation data from automatic stations in Jiangsu Province.The main results are as follows:1)The characteristics of frontogenesis during the Meiyu period in 2020 are significant.Heavy rain is associated with middle-low frontogenesis,with deformation frontogenesis being the main contributor.2)Heavy rainfall during the Meiyu period can be categorized into two types.Severe convective rainstorms exhibit a larger frontogenesis range,higher development,greater intensity,and more overlap between total frontogenesis and decomposition terms.However,stable rainfall shows opposite characteristics.3)Two typical cases,namely the strong convective rainfall event on“6.28”and the stable rainfall event on“7.11”are selected.Frontogenesis occurs along shear lines and in regions of significant pseudo-equivalent potential temperature gradient.Strong convective rainfall is observed near the main frontal zone and in high-energy zones of pseudo-equivalent potential temperature,indicating the presence of multiple secondary frontogenesis centers.Stable heavy precipitation,on the other hand,is concentrated near the main frontal zone.These different rainfall distributions arise from variations in triggering mechanism and precipitation properties.4)The vertical front zone in both processes tilts northward from low to high.In the“6.28”process,a notable transport of warm and moist airflow is observed on the south side of the frontal zone,with strong upward motion within the frontal zone.In contrast,the“7.11”process exhibits less pronounced features and weaker convection.The magnitude and impact of frontogenesis differ across various precipitation processes and stages.Rainstorms are primarily generated by divergence and deformation frontogenesis,while the tilting term frontolysis in convective precipitation and frontogenesis in stable precipitation.Quantitative analysis of each decomposition

关 键 词：江淮梅雨 锋生函数 暴雨 强对流 垂直锋区 

分 类 号：P458.121.1[天文地球—大气科学及气象学]