1951-2006年汕头雾变化的气候特征及影响因素分析

利用1951--2006年汕头气候资料，分析大雾天气的气候变化特征。结果表明：汕头年雾日总体呈明显下降趋势。20世纪90年代以前雾日相对偏多，90年代以后雾日明显偏少；大雾的逐月变化呈1峰1谷的特征，峰值出现在3月，谷值出现在8月；下半夜至翌日上午较易出现大雾。起雾时间为04：00—07：00，其中07：00最易起雾，雾消时间为04：00-12：00，09：00-11：00雾最易消散；雾日时静风概率为52％，风速小于等于3m／s的概率超过95％，不利于近地层空气的水平交换；雾日多伴有逆温层存在且逆温层具有底高较低、厚度较厚、强度较强的特点，不利于近地层空气的上下交换，因而雾日空气质量较差。

Characteristics of fog and its climatic controls from 1951 to 2006 in Shantou,Guangdong province

The characteristics of heavy fogs and their climatic controls were analyzed based on the climate data from 1951 to 2006 in Shantou, Guangdong province. The results indicate that the changes of fog days decrease obviously in Shantou. Fog days before 1990s are much more than after 1990s. The maximum and minimum fog days appear in March and August, respectively. The heavy fog often happens from late night to next morning. It usually appears from 04 ： 00 to 07 ： 00, especially in 07 ： 00. And the fog generally disappears from 04 ： 00 to 12 ： 00, especially from 09：00 to 11：00. The calm probability in fog days reaches about 52%. The probability of wind speed less than 3 m/s is more than 95 %, which is disadvantageous to the horizontal interchanges of air in the surface boundary layer. The inversion layer usually exists in fog days, and it is of the lower base height and thick depth as well as strong intensity, which is disadvantageous to the vertical interchanges of air in the surface boundary layer. That results in bad air quality in fog days.