河南省中北部一次区域性暴雨天气诊断分析

Diagnostic Analysis on a Regional Rainstorm Weather in North-central Henan Province

[目的]分析河南省中北部一次区域性暴雨天气过程。[方法]利用常规气象观测资料和河南省气象台站降水量资料,对2010年7月19日出现在河南省中北部的一次暴雨天气过程进行大气热力学和动力学诊断分析,研究暴雨发生时河南省中北部物理量场的特征和天气形势演变。[结果]西太平洋副热带高压加强西伸,中低层低涡的动力抬升和西南低空急流强盛的水汽输送,造成河南省中北部区域性暴雨天气过程。物理量诊断结果显示,深厚的湿层和持续的水汽辐合为暴雨的产生提供了充沛的水汽,正涡度平流中心自西北向东南发展和传播,有利于垂直运动的发展,中低层正涡度、中高层负涡度结构的维持,为这次区域性暴雨的产生提供了动力条件;中低层辐合、高层辐散的抽吸作用有利于低层垂直上升运动的加强,中低层露点锋的抬升作用触发不稳定能量释放;冷暖空气形成对峙,是造成区域暴雨的重要原因之一。TBB特征分析表明,整个强降水时段河南中北部TBB在-60～-50℃,其移动速度与西南涡移速相当;这条TBB低值带与河南暴雨发生的区域相对应,TBB最低值中心与降水最强中心基本一致。[结论]该研究为暴雨的短期预报提供科学依据。

[Objective] The research aimed to analyze a regional rainstorm weather process in north-central Henan Province.[Method] Based on the conventional meteorological observation data and the rainfall data of Henan Meteorological Observatory,the atmospheric thermodynamics and dynamics diagnosis analysis on a rainstorm weather process in north-central Henan Province on July 19,2010 was carried out.The characteristics of physical quantity field and the evolution of weather situation in north-central Henan Province when the rainstorm happened were studied.[Result] West Pacific subtropical high strengthened to extend westward.The dynamic lifting of low vortex at the middle and low layers and the strong water vapor transportation of southwest low-level jet caused the regional rainstorm weather process in north-central Henan Province.The diagnosis results of physical quantity showed that the deep moisture layer and the sustained water vapor convergence provided the plentiful water for rainstorm.The advection center of positive vorticity developed and spread from northwest to southeast,which was favorable for the development of vertical movement.The structure maintenance of positive vorticity at the middle and low layers and negative vorticity at the middle-upper level provided the power condition for the rainstorm generation.The pumping and suction effect of convergence at the middle and low layers and divergence at the high layer was favorable for the strengthening of vertical ascending motion at the low layer.The lifting effect of dew point front at the middle and low layers triggered the release of unstable energy.The confrontation of warm and cold air currents was one of the important reasons for the regional rainstorm.TBB characteristic analysis showed that TBB was from-60 to-50 ℃ in north-central Henan Province in the whole strong precipitation time,and the moving speed was equal to that of southwest vortex.The low value belt of TBB corresponded with the rainstorm occurrence zone in Henan,and the minimum value center of TBB was basically consistent with the strongest centre of precipitation.[Conclusion] The research provided the scientific basis for the short-term forecast of rainstorm.