【摘要】 利用NCEP/NCAR再分析资料和其他常规观测资料,对湖北省西南气流型暖区暴雨相关特征进行分析,结果表明:该类暖区暴雨主要发生在鄂东南地区,容易形成极端暴雨;低空急流是最主要的一个影响系统,低层强烈暖平流配合中层小股弱干冷空气,形成上干冷下暖湿层结,是本类暖区暴雨主要的不稳定建立机制;主要水汽输送通道有3条,水汽输送高度主要位于850 hPa附近,水汽辐合高度则位于850 hPa以下;暴雨发生过程中,0～1 km和0～3 km垂直风切变增长明显,其中0～3 km垂直风切变平均值可达11.6 m/s以上,对暴雨区的指示作用更显著;主要动力启动机制是低层风速辐合,而动力加强机制则来自于高低空急流耦合,在这个过程中,高空辐散加强,次级环流形成,从而形成强烈上升运动。更多还原

【Abstract】 Based on NCEP/NCAR reanalysis data and other conventional observation data,some characteristics on the southwest airflow warm-sector rainstorm in Hubei province were analyzed. The results show that the kind of warm-sector rainstorm mainly occurs in southeastern Hubei province,which easily form extreme rainstorms. The low level jet is the most important impact system for it.Strong warm advection at the lower level combined with weak dry and cold air in the middle layer,forming a stratification which is dry and cold at the upper level,wet and warm at the lower level,that is the main instability mechanism of the torrential rain in this kind of warm area. There are three main water vapor transport channels,the water vapor transport height is mainly located near 850 hPa,but the water vapor convergence height is below 850 hPa. The vertical wind shear of 0-1 km and 0-3 km increase obviously during the occurrence of rainstorm,the average value of vertical wind shear of 0-3 km is above 11.6 m/s,indicating the rainstorm area more significantly. The main dynamic starting mechanism is the convergence of low-level wind speed,while the dynamic strengthening mechanism comes from the coupling of upper and lower jet, in this process, the upper divergence is strengthened,and the secondary circulation is formed,thus forming a strong upward motion.更多还原