2012年7月发生于浙南山地的短飑线过程研究

山区强对流天气的发生条件十分复杂.选取2012年7月5日发生在浙江南部山区的一次短飑线天气过程,分析加密自动站、多普勒雷达和FY2E的TBB资料,并借助数值模拟手段,研究山地强对流天气发生发展的条件.利用自动站资料、叠加雷达和TBB资料,进行地面中尺度分析,对地面散度场特征进行了统计和分类,分析与山地强对流发生发展的关系,揭示山地强对流发生发展的前期特征.结果表明,来自东面海洋的东南气流易于在迎风坡前形成中尺度辐合区,这些低层辐合区是触发对流的有利条件.流场的辐合往往在回波单体出现前20min就已经存在.地面辐合线可造成低云的出现.中尺度山地触发了山地附近对流并沿着山地出现的辐合点和辐合线排列发展,最终形成中尺度的飑线,产生强对流天气.

Study on the genesis of a short squall line in mountains of Southern Zhejiang in 2012

Convection weather in mountainous terrain is complicated. In order to find out the conditions for initiating and developing severe convection in mountainous terrain, the squall line hitting Southern Zhejiang on 5th July 2012 was investigated. Based on the observation from dense automatic weather stations, and the data of Doppler radar and Temperature of brightness blackbody（TBB）, mesoscale analysis was performed and the divergence field on the surface was analyzed statistically to reveal the mountains＇ role in convection. Numerical simulation was also applied. Results indicate that the southeasterly wind from eastern sea is more likely to cause convergence zones at the windward side. These convergence zones are favorable to initiate convection. The convergence zones usually exist before the radar echoes appear. TBB signatures show that convergence lines on the surface contribute to the appearance of low cloud. Mesoscale mountains activate convection cells near the mountains and arrange them along convergence points or convergence lines, producing mesoscale squall line system, which results in severe weather.