| 北京连续降雪过程分析 |
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| 引用本文： | 王迎春,钱婷婷,郑永光.北京连续降雪过程分析[J].应用气象学报,2004,15(1):58-65. |
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| 作者姓名： | 王迎春 钱婷婷 郑永光 |
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| 作者单位： | 1.北京城市气象研究所, 北京 100089 |
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| 基金项目： | 北京市科学技术委员会项目H0 2 0 62 0 1 90 0 91，国家自然科学基金重点项目 40 2 3 3 0 3 6的资助 |
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| 摘 要： | 该文对2002年12月份北京出现的1841年以来历史上最长的连续6天的降雪天气进行了合成分析和诊断分析。北半球合成环流形势显示，连续降雪发生在东亚稳定的纬向环流形势下，其上游地区强大经向环流和阻塞高压使中纬度东亚和西太平洋纬向环流得以维持。东亚合成环流的垂直结构表明，连续降雪期间华北地区始终处于锋区中，并存在低空辐合、高空辐散的散度场垂直分布结构。卫星水汽云图显示出有水汽通道向河套倒槽云系输送水汽。华北地区的诊断分析表明，地面和边界层中山东地区分裂高压南侧向北回流的偏南气流是造成降雪的主要水汽通道。变形场的流场结构使水汽在北京附近辐合。垂直剖面展现了华北回流降雪天气近地面层的浅薄的冷空气垫，和暖湿空气回流在冷空气垫上的爬升，并在其上形成一个浅薄的饱和层。
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| 关 键 词： | 降雪 合成分析 诊断 回流 |
| 收稿时间： | 2003-01-15 |
| 修稿时间： | 2003年1月15日 |
Primary Analysis of the Longest-lasting Snowfall in Beijing |
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| Wang Yingchun,Qian Tingting,Zheng Yongguang.Primary Analysis of the Longest-lasting Snowfall in Beijing[J].Quarterly Journal of Applied Meteorology,2004,15(1):58-65. |
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| Authors: | Wang Yingchun Qian Tingting Zheng Yongguang |
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| Institution: | 1.Institute of Urban Meteorology CMA , Beijing , 1000892.Laboratory for Severe S torm Research , Department of Atmospheric Science ,College of Physics , Peking University , Beijing , 100871 |
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| Abstract: | Five-day snowfall, which occurred in Beijing on 19—23 December 2002 and became the longest-lasting snowfall since 1841, is compositely analyzed. Five-day composite circumfluence showed that the snowfall took place in the constant zonal circulation. During the period, there was a strong Mongolia High on the surface. And the ridge of high pressure protruded southward our country’s east. On 850 hPa, Hetao area has a northward trough, and Beijing lied in the positive vortex of the trough. On 500 hPa, a front crossing Asia from west to east located 40~45°N. On 300 hPa, Beijing situated positive vortex of the axis of the jet, which was straightly zonal. The vertical section indicated that Beijing was convergent on the low-lever whereas divergent on the high-level. And there were two fronts. In a conclusion, Beijing was controlled by the large-scale circumfluence that was in favor of snowfall.The analysis of Huabei area during the continuous snowfall showed that the deformation field locating the north of trough had evident vapor convergence. Moisture flux indicated that vapor came from the return flow of the Yellow Sea, but not the return flow of Bo Sea. The warm advection in the east of Hetao trough was the cause of ascending. |
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| Keywords: | Composite analysis Mongolia High Trough Front Return flow |
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