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2011年初冬华北南部回流暴雪诊断分析

Diagnostic analysis of the backflow snowstorm in early winter of 2011 in the southern part of North China

  • 摘要: 应用常规观测资料、自动站资料、加密观测降雪资料和GFS 0.5°×0.5°间隔6 h的再分析资料,对2011年11月29日发生在华北南部的暴雪过程进行动力诊断分析。结果表明:该暴雪天气的影响系统为高空槽和地面回流冷锋;水汽轨迹结果显示在暴雪过程中存在三股气流,即东北干冷气流、东南暖湿气流和西南暖湿气流;低层水汽主要来自东海,中层的水汽来自孟加拉湾和南海,暖湿气流在干冷空气之上爬升,在800 hPa左右形成锋区;冷平流是引起锋生的主要因子,锋生函数各项对锋生的贡献不同,垂直运动作用项对锋生贡献最大。

     

    Abstract: Data from conventional observations, automatic weather stations, intensive snowfall observations and GFS 6-hourly reanalysis with 0.5°×0.5° resolution are used to analyze the snowstorm occurred in the southern part of Hebei province on November 29, 2011. The results show that the upper trough and the surface cold front are dominant systems producing the snowstorm weather. Meanwhile, there are three major streams during the snowstorm event, i.e., cold airmass from northeast, and warm airmasses from southwest and southeast. Water vapor was mainly transported from the East China Sea at lower troposphere, while that of middle level comes from the Bay of Bengal and South China Sea. Warm moist air climbs over the cold and dry airmass and frontal zone is formed at about 800 hPa. Cold advection is the main factor for frontogenesis. While the contribution of each term in frontogenesis function is different, the tilting term is the largest contribution for frontogenesis.

     

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