攀西地区“7.7”暴雨雷达回波演变特征剖析

Anatomy of the Evolution of Radar Echo at "7.7" Heavy Rain in the Western Panzhihua

通过对攀西地区2006年7月6—7日暴雨过程的环流形势及新一代天气雷达回波演变特征分析表明:暴雨过程开始前本地大气中储存着丰富的不稳定能量,高低空风存在垂直切变,在地面冷空气和青藏高原切变线触发下对流强烈发展形成大范围暴雨。强降水超级单体风暴回波强度可达60dBz,暴雨回波长时间持续的主要机制是降雨回波不断地新生和合并,暴雨回波成熟时在强回波中存在较强的上升运动,暴雨云团中大于40dBz的强回波高度可达9km,顶高超过12km,垂直液态含水量达45kg.m-2,与此相对应的速度图上有逆风区、小气旋、辐合区等强降水特征出现。

The general circulation and the evolution characteristics of new-generation radar echo of the heavy rain on Jul. 7, 2006 （simply called as ＂7.7＂ rainstorm） in the western Panzhihua （called Panxi） are analyzed in detail. The result shows that before raining, there was a plenty of unstable energy, and a vertical westerly shear in the atmosphere. Near-surface cold air and a shear line over the Tibetan Plateau triggered an intensive convection and led to a heavy rain in a large area. The echo intensity of the super cell storm could reach to 60dBz. Long-sustained radar echo was the result of new genesis and merging of the echo. During the mature stage of radar echo, significant ascending movement took place within the strong echo area. The height of strong echo over 40dBz could be as high as 9,000 meters with its top height above 12,000 meters. Meanwhile, the amount of liquid water in the air column reaches 45kg· m^-2 and there were reverse wind, small-size cyclone and convergence as seen in the velocity chart.