石家庄市污染日特征及其天气背景分析

Analysis of Weather Background and Characteristics of Heavy Air Pollution Days in Shijiazhuang

对石家庄市2002年1月到2004年12月空气质量达到中度及以上典型污染日进行了统计分析,得出典型污染日的分布特点、对应的气象要素特征及3种天气型。结果表明:典型污染日多出现在采暖季节,出现时间具有相对连续性;污染日分为沙尘和非沙尘两类,气象要素特征前者表现为风速大、湿度小、多正变压等锋后特征;后者则表现为地面风小、湿度高、多逆温层、大里查逊数等稳定大气层结,这些均为锋前特征;还侧重指出由于石家庄的特殊地形作用,高压前部型是石家庄重污染出现几率最多的天气类型。并由此提炼出中度以上污染日的预报要点,可供空气质量预报业务参考。

A statistic analysis is made based on a large amount of observations during typical heavy air pollution days from January 2002 to December 2004 in Shijiazhuang. The temporal and spatial distribution of typical heavy air pollution days, the corresponding characteristics of meteorological elements, and three favorable synoptic patterns are revealed. The results show that most of typical heavy air pollution days take place in the heating period and have continuity in the temporal distribution; on dusty pollution days, there are strong winds, low humidity and positive pressure variation, and on non-dusty pollution days, there are weak winds, high humidity and stable stratification （temperature inversion, high Richardson number, etc. ） ; and a weather pattern with the highest occurrence probability of heavy pollution days, owing to the special topography of Shijiazhuang, is identified. Some useful hints for forecasting heavy pollution days are presented.