摘要
西风槽影响下鹤壁出现降水强度一般不大。2008年7月中旬,受西风槽及中低层切变线影响,鹤壁出现了一次连续性暴雨天气过程。利用常规天气资料、物理量场、卫星云图等诊断分析,结果表明,高空西风槽、中低层切变线及地面倒槽的共同作用,形成了深厚的上升气流,具备了暴雨产生的动力条件;中低空偏南急流源源不断地向鹤壁输送水汽,东南风和西南风在鹤壁的风向辐合,使水汽在鹤壁汇聚和上升,具备了产生暴雨的水汽条件;K指数由18℃迅速增至34℃以上,具备了产生暴雨的不稳定条件。200 hPa高空出现反气旋性强辐散,驱动低层辐合形成加强,对强降水得以维持发展具有主导作用。涡、散场表现为高、低层辐散、辐合双耦结构,总温度场400-700 hPa(>68℃)高能舌由四川经河南呈SW—NE向向东北伸展,对这次强降水具有很好的指示意义。降水落区出现在中低空能量锋区附近。
Though the precipitation intensity is generally not great influenced by westerly trough in Hebi. A eontinuous rainstorm occurred under the influence of westerly trough and mid - lower layer shear line in July 2008. The analysis based on conventional synoptic data, physical fields and satellite image showed that the interaction of high-level westerly trough, the mid-lower layer shear llne and the ground inverted trough, formed a deep updraft, provided the dynamic conditions for rainstorm generated; the southerly jet in the mid-lower layer continuous transporting water vapor to Hebi, and southeast wind and southwest wind converging in Hebi, to make water vapor aggregate and increase in Hebi, provided the water vapor conditions; the K index increasing from 18 ℃ to 34 ℃, created instable conditions. The anticyclonic strong divergence at 200 hPa altitude enhanced the formation of low-level convergence, made a leading role in the development and maintain of heavy precipitation. The coupling structure of upper divergence and lower convergence and high energy tongue development from southwest to northeast in the total temperature field at 400-700 hPa （ 〉 68℃ ） provided good indication to the heavy precipitation. Precipitation zone is in the vicinity of the mid-lower level energy frontal zone.
出处
《气象与环境科学》
2009年第B09期138-143,共6页
Meteorological and Environmental Sciences
关键词
西风槽
切变线
中小尺度系统
物理量场
连续性暴雨
westerly tough
shear line
meso-miso-scale system
physical fields
continuous rain-storm
