湖南隆回一次大暴雨天气过程综合分析

Synthesis analysis of a heavy rainfall process in Longhui,Hunan

利用常规探空资料、地面观测资料、自动气象站资料及水文雨量点资料、T213数值预报资料和卫星云图等,对湖南隆回2006年6月25日大暴雨天气过程进行综合分析.结果表明:暴雨区中上升运动和水汽辐合均大于周围区域,中低层为对流不稳定层结;大气层结的强烈不稳定,强烈的垂直运动,是形成暴雨的主要因素;700hPa的水汽来自孟加拉湾和南海,850hPa和500hPa的水汽来自南海;大暴雨发生前,低层有较强的水平能量输送和能量积聚,同时整个暴雨区的大气运动由下沉运动转变为上升运动;中低层Q矢量的辐合和大暴雨的落区、发生时段有较好的对应关系;低层正涡度、高层负涡度与低层强辐合、高层强辐散一致;"抽吸作用"和反馈作用加强低空辐合,促使暴雨发展.

Based on some routine sounding data,surface meteorological observation,automatic meteorological station and hydrological data,T213 numerical forecast and satellite pictures,the synthesis analysis was made on a heavy rainfall in Longhui in 2006.The results showed that the heavy rainfall happened on the condition of two-trough and one-ridge current pattern in the mid and high latitude of Eurasian.The trough line and shear line are the main influential systems;the important conditions causing the event are the strong instability of atmospheric stratification and severe vertical motion.The vapor at 700 hPa comes from the Bay of Bengal and South China Sea,and vapor at 850 hPa 500 hPa is from South China Sea.There must be strong energy transportation and accumulation in the low levels before the rainfall,and the atmosphere motion changed from descending motion to the ascending one in the whole rainfall area.The Q vector convergence at low levels is correlated well to the downfall area and time.The low-level positive vorticity and the high-level negative vorticity are in agreement well with and low-level convergence and high-level divergence.The effects of pumping and feedback strengthening lower convergence are favorable for the heavy rainfall.