长生命史超级单体结构特征与形成维持机制  

Structure Characteristics,Formation and Maintenance Mechanism of Supercell with Long Life Cycle

作　　者：吴海英[1,2] 陈海山[1] 刘梅[2] 沈阳[2] WU Haiying CHEN Haishan LIU Mei SHEN Yang(School of Atmospheric Science, Nanjing University of Information Science and Technology, Nanjing 210044 Jiangsu Meteorological Observatory, Nanjing 210008)

机构地区：[1]南京信息工程大学大气科学学院,南京210044 [2]江苏省气象台,南京210008

出　　处：《气象》2017年第2期141-150,共10页Meteorological Monthly

基　　金：公益性行业(气象)科研专项(GYHY201 506006);江苏省科技支撑汁划(BE2013730和BE2015731);江苏省自然科学基金(BK2013i459)共同资助

摘　　要：利用地面加密自动站、多普勒天气雷达等观测资料及NCEP再分析资料对2015年4月28日冷涡背景下发生在苏皖地区的强对流天气过程进行了分析,重点探讨了此次过程中导致苏南区域性冰雹的长生命史超级单体风暴结构特征及形成维持机制。结果表明:冷涡后部偏北急流的建立及其携至南下的冷平流,促进了条件性不稳定层结和深层垂直风切变的发展,为强对流天气的发生提供了有利的环境。地面中尺度低压及与之伴随的辐合线是对流风暴的触发机制之一。长生命史超级单体风暴起源于对流层中层,成熟阶段具有高度组织化的动力结构,风暴内伴有显著旋转特征,中层旋转最为明显,风暴内中层及以下对应较深厚的辐合区,风暴顶则表现出明显的辐散特征,有利于风暴内上升气流和风暴低层暖湿入流的增强,促进了低层较丰富的水汽向风暴内输送,导致对流风暴的垂直增长和强烈发展。冰雹出现前后,风暴顶高、质心高度呈现波动特征,冰雹出现在对流风暴顶高及质心高度迅速下降阶段,质心高度下降趋势更显著。超级单体风暴较长时间维持与对流层中层持续南下的冷平流、强垂直风切变的维持及风暴内旋转特征持续有关。Based on the surface dense automatic station data, Doppler radar data and NCEP/NCAR reanalysis data, the strong convective weather occurring over Jiangsu and Anhui Provinces on April 28, 2015 under the background of cold vortex was analyzed. Moreover, the structure characteristics, formation and maintenance mechanism of the supercell storm with long life cycle, which led to the regional hail in this weather process, were also significantly studied. The results showed that the formation of the northerly jet at the back of cold vortex and cold advection which was carried to the south promoted the development of conditional unstable stratification and deep vertical wind shear, providing a favorable environment for the occurrence of severe convective weather. Surface mesoscale depression and the accompanied convergence line were one kind of the triggering mechanisms. Supercell storm with long life cycle occurred in the middle troposphere and had highly organized dynamic structure at its mature stage. The storm had the significant rotation characteristics, especially in middle layer. The middle and low layer of the storm corresponded with deep convergence zone, while the top of the storm presented obvious divergence feature. Such veritical distribution of divergence field enhanced the intensity of rising flow within the storm and the warm, humid flow in the low level of the storm, making the abundant water vapor in low level transported into the storm, so the convective storm increased vertically and developed intensively. The top height of the storm and the centroid height showed features of wave motion before and after the hail occurring. The hail happened at the rapid descending stage of the above two heights, and the centroid height had more obvious descending trend. The maintenance of supercell storm was related to the constant southerly cold advection in the middle troposphere, the strong vertical wind shear and rotation feature inside the storm.

关 键 词：超级单体风暴 条件性不稳定 垂直风切变 旋转 

分 类 号：P458[天文地球—大气科学及气象学]