中文摘要：

利用NCEP 1°×1°再分析资料、常规观测资料和加密观测资料,对2007年12月17-28日冀中南地区连续性大雾过程的天气背景和雾长时间维持的原因及热力、动力结构特征进行了分析。结果表明,大雾期间我国中高纬地区冷空气活动偏弱,500hPa受稳定的暖性宽广高压脊控制,为维持数日不散的大雾天气提供了有利的环流背景;850hPa及以下多以偏东风和偏南风为主,偏东风不仅使雾区近地层温度降低,而且还将海域水汽送至雾区;同时偏南风也为雾区源源不断地输送水汽,特别是东北风的维持有利于强浓雾的形成,这是大雾持久不消散的主要原因;低层弱辐合、正涡度区、弱水汽辐合和900hPa以上的暖脊有利于雾的稳定维持和发展;由于强冷空气的到来导致大雾消散,破坏了稳定的逆温层结。

英文摘要：

Using the NCEP 1°×1°reanalysis data,conventional and intensified observation datasets,the background,genesis and thermodynamical structure for the long-drawn fog from 17to 28December 2007in central and southern Hebei Province are analyzed.The results show that the activity of weak cold air in middle and high latitudes,and the warm and flat high pressure ridge on 500hPa are the advantageous background of the long-drawn fog.The prevailing wind is easterly and southerly below 850hPa.The easterly do not only make the temperature of the surface-layer foggy zone to drop,but also transport the water vapor form the sea to the foggy zone such as the southerly.Especially the lasting westnorth wind is advantageous to the maintenance of the fog.The weak convergence,positive-vorticity area,low-level weak water vapor convergence,and warm temperature ridge above 900hPa are favourable to the long-drawn fog.The strong cold air destruct the inversion layer and finally make the fog dissipateing.