中文摘要：

2005年05号台风＂海棠＂登陆福建后,在外围云系里有个明显发展的中尺度对流云团经过温州东部及北部地区,引起了强降水,从而造成比热带风暴环流本身更具破坏力的强烈天气,因此研究台风内中尺度对流系统（MCS）的发展机制能够为预报台风灾害提供依据。文中使用中尺度静力模式WRF对台风＂海棠＂登陆过程进行了模拟,模式很好地模拟了台风登陆过程的路径、强度变化趋势和降水分布,尤其是模拟出了台风环流内的一次中尺度对流系统的发展过程,并利用模拟结果对台风环流内的这次中尺度对流系统进行了与之相关联的湿位涡分析,从而揭示了台风环流内中尺度对流系统发展演变的湿位涡特征。结果表明,在对流形成阶段,MPV1即对流不稳定为MCS的形成提供背景不稳定条件,由MPV2即湿等熵面的倾斜和水平风的垂直切变而引起的涡旋发展作为强迫机制：MCS形成的区域及东南区域中低层是强对流不稳定层,蕴含丰富的不稳定能量,倾斜上升运动把对流不稳定区具有强不稳定能量的暖湿空气向西北中层的中性层结区输送,由于θ_（ep）的减小,气旋性涡度增强,有利于形成对流,另一方面,由于湿等熵面倾斜和低空急流加强而引起的涡旋发展作为一种强迫机制激发对流不稳定能量得到释放,从而形成对流;在对流系统的发展阶段,由于低层的对流不稳定性进一步减弱,θ_（ep）进一步减小,气旋性涡度进一步增强,有利于MCS的增强,中层等θ_e线的倾斜度比绝对动量M等值线的倾斜度大,对应有条件对称不稳定区域,满足条件对称不稳定（CSI）条件,在湿等熵面倾斜和台风低空急流作用下引起的涡旋发展强迫对称不稳定能量释放,从而使得对流得以维持和加强。通过以上的分析给出了台风环流内中尺度对流系统发生发展的概念模型。

英文摘要：

Typhoon Haitang landed in Fujian in July 2005,then it moved northwest.During its movement,there was a mesoscale convective system（MCS） developing quickly within the outer spiral cloud band of the typhoon.The MCS caused heavy rainfall in the eastern and northern parts of Wenzhou,which brought more damage than the typhoon.A numerical simulation of the landing typhoon was performed by using the mesoscale model WRF in this paper.The model successfully simulated the typhoon track,the intensity tendency as well as the location of the heavy rainfall induced by the typhoon.Especially,the MCS development embeded in the typhoon circulation was well captured.A moist potential vorticity analysis associated with the MCS was carried out so as to reveal the moist potential characteristics of the MCS within the typhoon circulation.The results showed that,during the generation stage,convective instability characterized by MPV1 provided a favorable condition for the MCS.and the vorticity caused by the slantwise isentropic surface and the vertical shear of horizontal wind characterized by MPV2 offered an inspiring mechanism.The atmosphere exhibited strong convective instability at low levels over the MCS region and its southeast,which could supply plenty of erratic energy.The slantwise ascending air stream transfered the erratic energy northwest,where the stratification stability was small.Asθ_（cp） decreased,the cyclonic vorticity increased.On the other hand,the vorticity caused by the slantwise isentropic surface and the vertical shear of horizontal wind inspired the release of convective instability,and as a result the MCS formed.During the development stage,the cyclonic vorticity increased rapidly with a persistent decreasing ofθ_（cp）.Meanwhile,the inclination of isentropic line（θ_e） was bigger than the absolute momentum line（M） at middle levels,which exhibited the feature of conditional symmetric instability（CSI）,then the CSI was forced to release by the vorticity resulted from the slantwise isentropi