“麦莎”台风暴雨落区非对称分布的诊断分析

A DIAGNOSTIC ANALYSIS TO THE ASYMMETRIC DISTRIBUTION OF TYPHOON RAINFALL AREA

关键词:  台风暴雨  非对称分布  辐射亮温  水汽羽  诊断分析

Key words:  typhoon rainfall  asymmetric distribution  temperature black body  water vapor plume  diagnostic analysis

摘要:

利用FY-2C气象卫星资料、常规资料和NCEP再分析资料,对2005年第9号台风"麦莎"登陆后暴雨落区非对称分布的成因进行诊断分析,并讨论其动力学和热力学特征。结果表明:(1)FY-2C红外一通道辐射亮温(TBB)场能够清晰地揭示台风暴雨落区的分布以及造成这种非对称分布的云系结构特征;(2)水汽图像展示了此次降水过程中,对流层中上层主要的水汽型,来自南海和东海强盛的热带水汽羽直抵台风中心东部,中纬度地区的极锋水汽羽东移,其尾端并入台风北部,受二者共同作用,台风降水呈非对称分布;(3)台风中心附近的垂直流场、涡度、假相当位温和整层积分的水汽通量散度等物理量的非常规分布以及低层冷空气的契入,共同解释了台风云系的非对称结构及强雨区非对称分布的形成原因。

Abstract:

A diagnostic study to the cause leading to the asymmetric distribution of Tropical Cyclone MATSA(0509) rainfall was carried out by using FY-2C satellite data,conventional data and NCEP reanalysis data.Moreover,the characteristics of its dynamic and thermodynamic structure were investigated.Results show that(1) the distribution of TC rainfall area and the asymmetric characteristics of TC cloud system structure could be obviously found by FY-2C temperature black body(TBB) field;(2) The water vapor plume(WVP) of the mid-upper troposphere is a remarkable feature on water vapor images.On the one hand,a strong tropical WVP from the South China Sea and East China Sea stretches the eastern area of MATSA center.On the other hand,the mid-latitude WVP shifts eastward and its tail meets TC's north circumfluence.Together these lead to the asymmetric distribution of rainfall area;(3) The asymmetric structure of TC cloud system and distribution of rainfall area are illustrated by the effect of low-level cool air and the abnormal distribution of physical parameters such as the vertical flow field,vortex,pseudo-equivalent temperature and water flux divergence etc.