一条中尺度雨带的多普勒雷达回波特征及环境条件分析

该文利用3830/CC单多普勒雷达加密资料和Micaps客观分析资料, 对2002年8月22日在副高外围偏南气流影响下, 对流回波发展形成中尺度NNE — SSW向带状回波的演变及其环境条件进行分析。结果表明:带状回波是造成这次中尺度雨带的直接影响系统, 偏南暖湿气流源源不断沿着带状输送, 利于带状回波的维持和发展; 强降水主要发生在低层风随高度顺转 (暖平流)、高空有急流和出现逆风区的阶段, 副高外围偏南气流为带状回波的形成和发展提供了水汽和热力条件, 而高空倒槽为其提供了动力条件, 湿位涡的分布特征较好地说明了这一点, 带状回波和雨带出现在斜压不稳定和正压稳定而中低层为负涡度环流的潜在不稳定区中。

Doppler Radar Echo Feature and Environmental Condition Analysis of a Mesoscale Rain Belt

By using a single 3830-CC Doppler intensive weather radar data and Micaps objective data, a mesoscale NNE-SSW band echo evolution and environmental condition under south-southwest air stream around subtropical high were analyzed on August 22,2002. The results show that the mesoscale band echo is a direct influential system of the mesoscale rain belt and that a warm shear of wind, south-southwest jet flow and anti-wind zone are major radar echo features of the severe precipitation. The south-southwest air stream around subtropical high offers not only moisture condition, but also heat and dynamical conditions, which are indicated by moist potential vorticity distribution. The band echo and rain belt locate in the zone between barotropic instability and baroclinic stability with a potential instability of negative vorticity circulation in the lower layer.