首都机场大雾的分类特征和统计分析

普查了1999～2006年首都机场逐时的风、温、压、湿和能见度资料以及首都机场自动观测系统(AWOS)的连续自动记录资料,对出现的大雾过程进行分类,并分别统计分析了各类大雾出现的时序特征、背景场特征以及出现前和消失时的气压、风场等物理量特征.分析发现首都机场的大雾过程以辐射雾为主,出现前湿度递增,风向以东南风和东北偏东风较多;平流雾以东南和偏东方向平流为主,出现前湿度突增,能见度急速降低,81.8%的平流雾达到了重雾的标准,重雾的出现率高,对飞行危害最大.锋面雾多为本站处于冷锋前部,伴随平流或辐射过程的持续性大雾,出现时间早于辐射雾,多集中在傍晚到夜间,持续时间长,锋面过境后大雾才能消散.

Statistic Analysis and Classification of Fogs at Beijing Capital International Airport

The classification and analysis of fogs at the Beijing Capital International Airport (BCIA) are made based on the statistical analysis of the hour to hour fog observation data and the AWOS (Automatic Weather Observation System) data from BCIA from 1999 to 2006 (including wind, temperature, pressure, relative humidity and visibility). Each type of fog is statistically studied from the aspects of the temporal and background characteristics, pressure and wind variation characteristics, etc., during the occurrence and dissipation of fogs. The results show that radiation fogs occur most frequently at BCIA, before which there appears a gradually increasing humidity with the wind direction being SE or NNE. Advection fogs form generally after the rapid increase of humidity and the rapid decrease of visibility, inducing most serious damage to flighting, of which 81.8% reached the heavy fog standards. Front fogs occur mostly before a cold front, being persistent, mostly along with an advection or radiation process, appear usually earlier than radiation fog, mostly in the later afternoon and evening with a longer duration,and disperse generally after the front.