【摘要】 利用 1 96 1～ 2 0 0 1年有烟日观测资料 ,统计分析了 4 1年中 ,兰州市城区大气受烟尘污染的变化。结果表明 :1 96 1～ 1 984年污染日在 1 1 9～ 2 0 1天间徘徊 ;1 985～ 1 988年是污染“严重期” ,年平均污染日达 2 2 4天 ;1 996～ 2 0 0 1年为显著“好转期” ,年平均污染日 6 6天。一年中主要污染段是 1月和 1 1、1 2月 ,污染日占全年的 4 9%。在污染日 ,大气水平能见度具有明显的日变化 ,能见度最差 ,污染最严重的时间是 1 1～ 1 4时。更多还原

【Abstract】 The relationship between variation and meteorological condition of atmospheric pollution in the Lanzhou City is analyzed for the period of 1961—2001 by using the observational data of smoke days. The results show that the pollution days are about 119—201 in 1961—1984,serious pollution is in 1985—1988,the mean annual pollution days are 224,obvious improvement is in 1996—2002,and the mean annual pollution days are 66. In a year,the main polluting periods are January and from November to December,and the rate of pollution days is 49 percent. In pollution days,the visibility has distinct daily variation,the shortest distance of visibility and the most serious pollution phase are from 11:00 to 14:00.更多还原