2008-2018年江南暖区暴雨特征

Statistical analysis of the characteristics of warm-sector rainstorms in the southern part of the Yangtze River during the period of 2008-2018

摘要:

利用2008-2018年常规地面资料、探空站资料、逐小时自动站降水资料，NCEP/NCAR再分析资料及FY2E卫星TBB资料对江南暖区暴雨进行了统计分析和可能影响因子研究。2008-2018年共发生65次江南暖区暴雨，分为切变型、副高型、副高和切变相互作用型和西南急流型4类，可进一步细分为暖切变型、冷切变型、暖切变与副高相互作用型、冷切变与副高相互作用型、副高边缘型、副高内部型和西南急流型，其中以冷切变型最多且分布最广，西南急流型最少，暖切变型降水强度大且极端性明显。江南暖区暴雨多出现于江南中部内陆平原地区，其与华南暖区暴雨相互独立。东北冷涡南侧低槽对江南暖区暴雨的作用显著，高原槽的影响次之。江南暖区暴雨发生时多伴随急流，春季和初夏时节伴随低空急流的概率要远远高于盛夏时节，两支影响江南暖区暴雨的水汽输送通道均通过西南急流向江南地区输送水汽。江南暖区暴雨除西南急流型（具有较低的对流指数）和副高内部型（具有较高的对流指数）外普遍具有较为明显的CAPE（>500 J/kg）和K指数（>35 K），而CIN（<100 J/kg）和LI（<0）则较小，LCL大部分处于920～980 hPa，LFC处于800～900 hPa，0℃层高度处于4 500～5 500 m，假相当位温处于340～360 K。

关键词:江南;暖区暴雨;统计分析

Abstract:

In the present paper,the spatial and temporal distribution characteristics of warm-sector rainstorm (WR) cases which have occurred in the southern part of the Yangtze River during the period of 2008-2018 are analyzed,and the underlying contributing factors are investigated using NCEP/NCAR reanalysis data and FY2E TBB data.There are a total 65 warm-sector rainstorm (WR) cases which occurred in the southern part of the Yangtze River during the period of 2008-2018,which can be divided into four types:shearline,subtropical high (SH),interaction between shearline and SH,and southwest low-level jet.These can be further subdivided into warm shearline,cold shearline,interaction between warm shearline and SH,interaction between cold shearline and SH,SH margin,SH internal and southwest low-level jet.Among these seven types,the cold shearline type has the greatest number and widest distribution,while the southwest low-level jet type has the smallest number.In addition,precipitation in the warm shearline type exhibits the characteristic of extremity.Warm-sector rainstorms in the southern part of the Yangtze River are mostly found in the inland plains,which are independent of those occurring in southern China.Among the middle level weather systems,WRs are mostly affected by the northeast cold vortex,followed by plateau systems.WRs are often accompanied by low-level jets,and have a much higher probability to occur in spring and early summer than in boreal summer.Two water vapor transport channels which affect the WR both transport water vapor to the southern part of the Yangtze River via the southwest low-level jets.With the exceptions of the SWLLJ and SH internal types,the other WRs in the southern part of the Yangtze River are characterized by obvious CAPE and K index,low CIN and LI,while LCL is in the range of 920-980 hPa,LFC 800-900 hPa,Thetase 340-360 K and H0 4,500-5,500 m.

Key words:south of Yangtze River;warm-sector rain storm;statistical analysis