中尺度冷涡切变暴雨多普勒雷达特征分析

利用天气形势场、物理量场、新一代雷达产品资料对2008年7月17日下午到夜里,豫北、鲁西、冀南地区出现的区域性暴雨天气进行多尺度诊断分析.分析结果显示:较弱的冷性低涡切变本身并不能造成强降水天气,当低涡东移遇副热带高压西北边缘较强暖湿气流时得到加强,在低涡东侧副热带高压边缘切变上产生暴雨天气.冷涡暴雨低层有明显的东北气流冷垫,加强了其动力上升运动,水汽输送依赖于对流层中层的西南气流,中层水汽辐合非常明显.在新一代雷达产品图上显示:较稳定的大范围中等强度回波能产生较强降水.中低层风场为暖平流加辐合,有利于暴雨的形成,中低层较大的垂直风场切变给对流云的形成提供动能,有利于暴雨的产生.

The Characteristics of Doppler Radar Product of a Rainstorm Caused by the Mesoscale Cold Eddy Shear

By using the weather situation,physical quantity field,a new generation of radar product information,a rainstorm process in the north of Henan,the east of Hebei and the west of Shandong from afternoon to night on July 17,2008 was analyzed. The result shows that weaker cold vortex shear itself did not cause heavy rain weather ,when the low vortex eastward in the stronger subtropical high in the northwest edge of wet system was improved and the low vortex on the east side on the edge of the subtropical high shear caused rain storm weather. Cold eddy rain significantly lower the northeast cold air cushion,strengthened its upward movement of water vapor transmission relied on the southwest jet stream of middle troposphere,middle water vapor convergence was very obvious. Products in a new generation of radar chart shows that the stability of a wide range of medium intensity echo can produce strong precipitation. In the low-level wind field there was warm advection and convergence ,which was conducive to the formation of the heavy rain. The low-level larger vertical wind shear provides kinetic energy for the formation of convective clouds,is advantageous to the heavy rain .