华北地区一次局地暴雪天气过程的诊断分析

应用常规资料、卫星云图和多普勒雷达资料,对2007年春季承德市暴雪天气从形成的大尺度背景、水汽条件、动力条件进行分析。结果表明：东部高压脊的阻挡导致南北低值系统的合并加强,它的移动缓慢造成了这次暴雪天气。低层辐合和低空急流的建立造成大范围的水汽辐合和源源不断的水汽输送,深厚的大气湿层为大的降水提供了有利的环境条件;散度场、垂直速度场、k-螺旋度的高低空配置和时空变化是暴雪天气发生、发展的动力条件。结合红外卫星云图,分析实时的多普勒雷达资料对预测暴雪天气的发展变化至关重要。

Analysis of a Local Snow Storm in Spring of 2007 in North China

Based on the conventional data,satellite cloud images and Doppler Radar data,the snow storm weather occurred in spring of 2007 in Chengde was analyzed from the large-scale background,water vapor and dynamic conditions.The results indicate that the block from the eastern pressure ridge leads to the merger and intensification of the north and the south low-pressure systems,and moving slowly of the low-pressure system results in this storm event.The convergence in the lower level and the foundation of low level jet made largescale water vapor convergence and continual water vapor transmission,and the deep-thick atmosphere wet layer provides a favourable surrounding condition and the divergence,vertical velocity and k-helicity fields are dynamic conditions for this heavy rain.