一次华北飑线的阵风锋天气过程分析

利用常规气象观测资料、加密自动站观测资料和雷达探测等资料,对2013年8月4日晚上华北一次飑线的阵风锋引发的雷暴、大风等强对流天气的特征和成因进行了分析,结果表明:地面冷锋与前倾槽的配置构成了有利的大尺度环流背景,地面中尺度高压外流冷空气与环境风场形成的中尺度辐合线,使得对流活动加剧,促使新的雷暴生成或加强。飑线成熟阶段具有明显的波动特征,并向右向发展。阵风锋首先产生于飑线的强雷暴群前,并随着飑线的增强而增强;阵风锋的维持主要依靠风暴持续的下沉气流,下沉气流减弱后阵风锋会随之减弱。飑线及阵风锋过境时均伴有气象要素的剧烈变化,在系统发展强盛时,阵风锋过境气象要素的变化幅度大于飑线的变化,其余时段则偏弱。飑线减弱以后,阵风锋还会维持一段时间,这需要加强系统的监测。

Analysis on a Gust Front of Squall Line Event in North China

Using conventional observational data, surface meteorological observation data and Doppler radar data, the weather characteristics and causes of the gust front in North China on 4 August 2013 are analyzed. The results indicate that the configuration of ground front and forward tilting trough is the favorable large scale circulation background of the gust front. Between the outflow cold air of surface mesoscale high and environment wind forms a mesoscale convergence line, which makes the convective activity get intensified, causing new thunderstorms to generate or be strengthened. In the mature stage, squall line has distinct characteristics, and develops to the right. At first, the gust front forms in front of severe thunderstorms of the squall line. The stronger the squall line, the stronger the gust front. The maintainance of the gust front relies mainly on the continued sinking airflow of the storm. The gust front weakens after the sinking airflow drops off. Meteorological elements have dramatic changes as the squall line and gust front are passing through the area. When the system develops stronger, the variation of meteorological elements of gust front is greater than that of squall line, but is weaker in the rest time. After the squall line gets weakened, the gust front still also maintains for a period of time, which needs to be observed more carefully.