台风“麦莎”的强度对台风前部飑线发展过程影响的研究  

Impact of Typhoon Intensity on the Development of a Pre-Tropical Cyclone Squall Line

作　　者：刘佳[1] 沈新勇[1] 张大林[2] 许映龙 毕明玉[1] 

机构地区：[1]南京信息工程大学气象灾害省部共建教育部重点实验室,南京210044 [2]马里兰大学大气和海洋科学系,美国马里兰州20742 [3]国家气象中心,北京100081

出　　处：《大气科学》2013年第5期1025-1037,共13页Chinese Journal of Atmospheric Sciences

基　　金：国家重点基础研究发展计划(973计划)项目2013CB430103;国家公益性行业(气象)科研专项GYHY200806009;国家自然科学基金资助项目41075039;41175065;江苏省普通高校研究生科研创新计划项目

摘　　要：对2005年8月5日16时(UTC,下同)至6日00时发生的一次台风前部飑线过程进行了数值模拟,分析表明:台前飑线在母体台风和副高之间的湿区生成。台风为这次台前飑线过程提供了有利的条件,包括强的低空急流输送充沛的水汽,强的不稳定环境产生大的对流有效位能以及强的地表辐合,使得初始的离散的对流单体组织发展形成台前飑线。成熟时期的台前飑线虽然比中纬度和热带飑线的变压强度小,但是具有更强的低层暖湿空气入流,中层的入流范围也更加宽广。敏感性试验结果表明:台风强度越强,其台前飑线的回波强度越强,移动速度更快,生命史也更长。强台风使得低空垂直风切变更大,有利于台前飑线的生成和发展,在台前飑线发展成熟后,低空垂直风切变强度减小,不利于台前飑线的维持,加之低空水汽输送的减少,使其逐渐趋向衰亡。A severe pre-TC （Tropical Cyclone） squall line that preceded Typhoon Matsa （2005） was investigated using the non-hydrostatic ＂Weather Research and Forecast＂ model. The results showed that this pre-TC squall line formed in the moist transition zone between the parent TC and a subtropical high. It was found that Matsa may have contributed to convective development in the squall line by producing conditional instability and enhancing low-level moisture convergence, leading to the organization of the early discrete convection into a linear rainband. Although the pre-TCsquall line caused fewer surface pressure perturbations at its mature stage than is typically observed at mid-latitudes, it exhibited stronger moisture convergence in the boundary layer and a larger area of inflow in the mid-troposphere. Sensitivity analyses showed that stronger TCs give pre-TC squall lines that are longer lived and faster moving, with more intense rainfall. The results showed that a stronger TC tends to produce more low-level vertical wind shear in the transition zone, which favors the organization of early discrete convection into a squall line. However, low level vertical wind shear in the vicinity of the pre-TC squall line decreases when the mature stage is entered. This, in addition to the likelihood of a reduced low-level moisture supply, appears to be one of the factors that is unfavorable for the pre-TC squall line being maintained.

关 键 词：台风麦莎 台前飑线 低空垂直风切变 位涡反演 敏感性试验 

分 类 号：P444[天文地球—大气科学及气象学]