北海夏季一次强对流天气过程分析

Analysis on A Severe Convective Weather Process in Beihai in Summer

[目的]分析北海夏季一次强对流天气过程。[方法]利用Micaps常规资料和北海单站站点资料、雷达资料,对2010年8月北海市的一次强对流天气过程分析。[结果]850和700 hPa在越南北部和北部湾沿海的气旋性低压环流有利孟湾西南气流的输送,为强降雨提供充足的水汽条件;弱冷空气和东南暖湿气流相互作用是此次强降雨过程的主要原因;强降雨的落区与水汽的辐合有关,东南—西北向的水汽通量散度场的维持有利桂南地区强降雨的的持续;在强降雨之前,北海站高低层正负涡度均突然加强,对对流的产生十分有利;此次强降雨过程垂直速度随高度的变化从开始就由正值转为负值,这个转折对强对流天气的产生有预示预警的作用。[结论]该研究为夏季广西沿海强对流天气预报提供理论依据。

[Objective] The research aimed to analyze a strong convective weather process in Beihai in summer.[Method] By using Micaps conventional data and the single station site information,radar data in Beihai,a strong convective weather process in Beihai City in August,2010 was analyzed.[Result] 850 and 700 hPa cyclonic low-pressure circulation in the north of Vietnam and Beibu Gulf coast was favorable for the transportation of Bengal Bay southwest airflow,which provided the sufficient water vapor condition for the strong precipitation.The interaction of weak cold air and southeast warm wet airflow was the main cause of the strong rainfall process.The strong precipitation falling zone related to the water vapor convergence.The maintenance of water vapor flux divergence field in southeast-northwest direction was favorable for the duration of strong precipitation in the south of Guangxi.Before the strong precipitation,the positive and negative vorticity in the high and low levels in Beihai station both abruptly strengthened,which was very favorable for generating the convection.The vertical velocity in the strong precipitation process turned from the positive value at the beginning to the negative value as the height variation.The turning had the indicated and early-warning roles on the generation of strong convective weather.[Conclusion] The research provided the theory basis for the strong convective weather forecast in Guangxi coast in summer.