【摘要】 西宁是我国空气污染最严重的城市之一,冬春季节尤为严重,特别是当春季受到强沙尘暴影响时,会产生5级以上的严重空气污染。这除了当地污染源过量排放和外来沙尘输送外,当地大气扩散条件也是主要原因之一。利用西宁市2000年1月至2002年12月的各种常规气象观测资料和降水pH值资料,计算分析了西宁地区月、季、年各种逆稳层日数和混合层厚度,结果表明,西宁地区月逆温平均日数和月平均混合厚度基本呈反位向。冬半年各种逆温出现的总日数一般在15～24d之间,而夏半年在7～12d之间,前后二者相差一半。月平均混合厚度夏半年高,而冬半年低;季节变化是冬季平均混合厚度最低,春、夏季较高,秋季平均混合厚度介于春季和冬季之间,年最低和最高混合层厚度的平均年变差为145m。月逆温平均日数多(少)、月逆温厚度平均偏高(低),而月平均混合厚度偏低(高)。pH值月、季平均值与月、季平均混合厚度的变化趋势基本一致。混合层厚度高(低),湍流运动强(弱),空气在垂直和水平方向交换时间短(长)、扩散能力强(弱),pH值大(小)。更多还原

【Abstract】 Xining is one of the most severe cities suffered from air pollution in China, where pollution is especially heavy in winter and spring time. The heaviest air pollution more than five grades will happen in Xining when super-severe dust storms occur in springtime. In this paper, the meteorological characteristics about air pollution such as inversion, mixing depth and atmospheric stability were analyzed based on routine meteorological data from Xining observational station during January 2000 to December 2002. The analyzed results are as follows: The annual variation phase of monthly occurrence days of inversion is opposite to that of monthly mean mixing depth in Xining. Usually the sum of monthly occurrence days of inversion ranges from 15 to 24 days in cold half of a year but only from 7 to 12 days in warm half of a year. Monthly mean mixing depth is high in warm half of a year but low in cold half of a year. The maximum of them is in summer and the minimum is in winter. So it is an important reason that air pollution is heavier in winter than in summer in Xining City. In addition, the pH value of precipitation in Xining is the highest in May and June. This phenomenon is relative with frequent occurrence of dust-storm there at that time, because the dust from dust-storm can depress the acidification of precipitation due to air pollution. Besides, the improvement of atmospheric diffusion condition in summer is also beneficial to reducing air pollution. This can decrease the acidification of rainfall.更多还原