海风锋在渤海西岸局地暴雨过程中的作用

The Role of Sea Breeze Front in Local Storm of Bohai Coast

利用常规观测资料、地面加密自动站资料、多普勒雷达观测资料及中尺度TJ-WRF模式输出资料,对2009年7月6日天津宁河地区出现的暴雨天气过程进行了分析,重点分析了渤海湾海风锋对沿岸局地暴雨的触发机理。结果表明:此次局地暴雨过程是在有利天气背景条件下发生的,暴雨发生地存在局地层结不稳定和较好的水汽条件。海风锋本身有一辐合抬升区,区域内有弱对流存在;当海风锋移到局地存在层结不稳定且水汽充足的区域,其抬升区的辐合上升运动迅速加强,从而触发该地区雷暴的新生发展;海风锋与迎面移来的雷暴相遇,会对雷暴的加速发展起到加强作用。利用中尺度WRF模式输出资料进行分析看到,两条辐合线相交处易激发出强雷暴,雷暴出现在近地层大气暖干区的北端、湿空气的交汇处;海风锋对雷暴的新生发展有明显的触发抬升作用。

Using the data obtained by conventional observations,ground densified automatic weather stations, Doppler radar observations and mesoscale TJ-WRF model,we analyze the heavy rain occurring on 6 July 2009 at Ninghe District of Tianjin and highlight the trigger mechanism of coastal local storm caused by sea breeze front of the Bohai Gulf.The results show that the heavy rain occurred in the favorable weather conditions,and there were local instability and adequate vapor conditions.Sea breeze front itself has a convergent uplift area where weak convection exists;when sea breeze front moves to the unstable and adequate vapor areas,it will strengthen the convergence positive movement of convergent uplift area and lead to the new storm development.The meeting of the sea breeze front and thunderstorm will play a strengthened role in its development.By analyzing the data obtained by mesoscale WRF model,we can see that at the warm and dry ground in front area near the north end of the wet air interchange,the intersection of the two convergence lines is easy to stimulate strong thunderstorms,and thunderstorm accrues at the intersection of the north of the subaerial warm and dry front zone and humid air.Sea breeze front plays an important role in the development of the thunderstorm.