梅雨锋上两类中尺度对流系统形成的边界层特征  

The boundary layer characteristics of two types of mesoscale convective systems along a Meiyu front

作　　者：许长义[1,2,3] 林永辉[2] 管兆勇[1] 

机构地区：[1]南京信息工程大学大气科学学院,江苏南京210044 [2]中国气象科学研究院灾害天气国家重点实验室,北京100081 [3]天津市滨海新区气象局,天津300457

出　　处：《大气科学学报》2012年第1期51-63,共13页Transactions of Atmospheric Sciences

基　　金：国家自然科学基金资助项目(40745026;40875035);公益性行业(气象)科研专项(GYHY(QX)2007-06-20);中国气象科学研究院基本科研业务费专项(2007Y002);灾害天气国家重点实验室自主研究专项(2008LASWZ103);国家科技支撑计划课题资助项目(2007BCA29B02)

摘　　要：采用具有较高时空分辨率的地面观测资料以及WRF(Weather reasearch and forecasting)模式输出资料,分析了2009年6月29—30日梅雨锋暴雨过程中两类不同的中尺度对流系统(mesoscale convective system,MCS)边界层特征及边界层对两类MCS的触发维持机理,重点分析了海平面气压场特征、边界层冷池、干线及其在MCS中的影响。结果表明:两类中尺度对流系统的海平面气压特征存在着明显的差异,对流爆发阶段地面风场存在辐合线,再次激发阶段气压场呈"跷跷板"型的中尺度扰动,即由前置中低压和后置中高压组成,最强的对流带位于中低压和中高压之间的过渡区内;边界层辐合线是第一类中尺度对流系统(MCS1)维持的重要因素;MCS1爆发后边界层冷池生成,冷池前的冷出流与低层环境风产生的强辐合触发了第二类中尺度对流系统(MCS2);存在于中低压和中高压之间的中尺度干线是MCS2的重要特点之一。By using the surface observational data at high spatial and temporal resolutions together with simulations of the Weather Research and Forecasting model, the characteristics of atmospheric boundary layer and mechanisms of two different types of MCSs（ mesoscale convective systems） which led to the Meiyu front rainstorm that occurred over the Yangtze River basin during 29-30 June 2009 are analyzed, focusing on sea level pressure field, boundary layer cold pool, dryline and its effect in MCS. The results show that there are obvious differences for the sea level pressure fields corresponding to the two distinct MCSs （referred as MCS1 and MCS2 ）. MCS1 corresponds to boundary layer convergence line while MCS2 is composed of a mesolow and a mesohigh which are located in front of and behind the severe convective zone, respectively. The severe convective zone occurred in the transition zone between the mesolow and mesohigh. The boundary layer convergence line is an important factor in maintainingMCS1. The convergence between the boundary outflow before the boundary layer cold pool caused by the developing process of MCS1 and lower-layer wind triggered MCS2. The mesoscale dryline in the transition zone was an important characteristic of MCS2.

关 键 词：中尺度对流系统 边界层辐合线 边界层冷池 干线 

分 类 号：P458.121.1[天文地球—大气科学及气象学]