南京一次局地大暴雨的β中尺度对流系统结构分析  

Structure analysis on the meso-β scale convective system in a local torrential rain of Nanjing

作　　者：沈阳[1] 沈安云 吴海英[1] 尹东屏 

机构地区：[1]江苏省气象台,南京210008 [2]滁州市气象台,安徽滁州239000 [3]江苏省气象服务中心,南京210008

出　　处：《气象科学》2015年第6期791-798,共8页Journal of the Meteorological Sciences

基　　金：中国气象局气象关键技术集成与应用(重点)项目(CMAGJ2014Z02);江苏省科技支撑项目-社会发展项目(BE2011818)

摘　　要：利用WRF中尺度模式,对2007年7月发生在南京地区的一场局地大暴雨过程进行了数值模拟。通过大尺度环流、流场以及有关物理量等特征结构分析表明:在南京地区产生局地暴雨的直接影响系统是一个β中尺度对流单体。在成熟期具有暖性对流涡柱的特征,涡度的发展较散度具有一定的滞后性,其暖心结构和假相当位温分布与热带气旋极为一致。并且该对流系统的垂直环流在成熟期表现出了一些类似超级单体的环流特征,证明了普通单体风暴具有向局地强风暴发展的潜力。从分析液相及冰相粒子混合率的垂直分布表明:对流单体发展的成熟期,冻结高度之上有过冷水与冰相粒子共存,过冷水分布最广的时期与系统最强降水时段对应良好。这意味着淞化过程可能是导致对流系统降水增幅的一种机制。由水汽通量散度分析,对于预报对流系统的发生位置和时间具有一定的指示意义。本次过程中流场散度项是决定水汽通量散度分布的关键因素,水汽平流项的贡献甚微。A numerical simulation on a regional torrential rain in Nanjing in July, 2007. was carried out by using WRF meso-scale model. Results show that the direct influencing system of this heavy rain is a meso-β scale convective cell, which is characterized by warm convective vorticity cylinder in its mature period, and whose development was lagging compared with divergence with warm-core sturcture and pseu- do-equivalent temperature distribution similar to tropical cyclone. Moreover, the vertical circulation exib- its some features of super cell, which proves that normal cell tends to develop into local strong storm. The vertical distribution of liquid and ice particle mixing ratio show that the supercooled water coexists with ice and snow particle above freezing height and the widest distributed period of suprecooled water is well corresponding with the strongest rainfall period of system, which might be a mechanism of precipitation enhancement for convective system. The analysis on moisture flux divergence held predict the location and initial time of convection occurrence. In to determine the distribution of moisture the process, the flux divergence can be considered as a key used flux divergence, but the water vapor advection term contributes

关 键 词：暴雨 Β中尺度对流系统 数值模拟 

分 类 号：P458.121.1[天文地球—大气科学及气象学]