冷涡背景下飑线过程统计分析

文章首先给出冷涡的定义,根据其定义,利用2008-2013年4-9月的天气图识别出73个冷涡,然后根据飑线的标准筛选出符合条件的飑线过程。利用多普勒雷达资料和1°×1°6 h的NCEP FNL资料,对飑线的时空分布、移动特征、形成、消散方式以及飑线和冷涡的关系等方面进行详细分析。结果表明:(1)2008-2013年6年共识别出73个冷涡、17条飑线,飑线主要形成于我国江淮流域、华北地区和东北地区。(2)飑线的发生有明显的月变化和日变化,约58.8%的飑线发生在7月,52.9%的飑线发生在午后到傍晚。(3)飑线主要形成在冷涡的南部,在冷涡的不同时期飑线形成的位置有所不同。(4)飑线一部分受西风带系统影响自西向东偏南方向移动,另一部分由西北向东南方向移动,具体移动方向具有不一致性。冷涡背景下的飑线移速较快。(5)本文统计的冷涡背景下飑线过程大都伴随短时强降水,主要形成方式为嵌套区线型(EA型),主要消散方式为颠倒破碎面型(RBA型),EA型飑线多产生于高潮湿环境中。

Analysis of Squall Lines Under the Background of Cold Vortex

Cold vortex is identified based on the definition of cold vortex, and 73 cold vertexes during 2008-2013 are identified. According to the screening criteria of squall line, the qualified squall lines are screened out. Digital radar mosaics of composite radar reflectivity are used in this study to perform the survey. Detailed analyses are carried out on the spatio temporal distribution, moving characteristics, formation, dissipating way of squall lines and the relationship between cold vortex and squall lines. The results show that (1) 73 cold vortexes and 17 squall lines during 2008-2013 are identified, which mainly formed in Huaihe River Basin, North China and Northeast China. (2) Squall lines have obvious features of monthly and diurnal variations, with nearly 58.8% in July, and 52.9% from afternoon to evening. (3) Squall lines form mainly in the south of the cold vortex. During the different stages of cold vortex, squall line develop in different positions. (4) Some squall lines move towards east south influenced by the mid latitude westerlies weather system, and others move from northwest to southeast. Due to the influence of the cold vortex system, squall lines move fast. (5) Most squall lines under the background of cold vertex are accompanied by heavy rainfall. The main forming mode is embedded areal (EA), the main dissipation mode is reversed broken areal (RBA), and EA type squall lines are often seen in highly humid environment.