摘要：通过对杭州市区 1981~2006 年能见度、主要污染物的观测和研 究，探讨市区能见度下降的原因。 结果表明，能见度具有明显的下降趋 势，20 世纪 80 年代的平均能见度为 10 km 左右，本世纪初减小到 7 km 左右。 在低能见度的天气现象中主要是霾。 能见度的季节变化非常明 显，夏季好冬季差。 当污染物浓度和相对湿度增加时能见度减小。 能见 度与污染物、气象因素的多元回归分析表明相对湿度、NO₂、气溶胶细 粒子 PM_2.5 是影响能见度的主要因子。 

关键词：大气能见度；气溶胶；霾；影响因子

Abstract：Based on the study and monitoring of visibility and major air pollutants in Hangzhou City，the major causes of the decrease of visibility were discussed in urban area. The results showed that the visibility de creased significantly, the average values of visibility was about 10 km in 1980s，and about 7 km in first this centure. The major weather phe nomenon in the lower visibility was haze. The seasonal variation of visibil ity was very obvious，it was best in summer and worst in winter. The visi bility was decreased when the pollutants and relative humidity increased. The results of the multiple regression analysis between the visibility and pollutants and meteorological factors demonstrated that the relative humid ity，NO₂，aerosol particles PM_2.5 were the three major factors which affected the visibility of Hangzhou urban area. 

Keywords：visibility；aerosol；haze；effect factor