天津市区秋冬季大气气溶胶散射系数的变化特征

摘要

With the analysis on the aerosol scattering coefficient in urban site of Tianjin in September 2006 to February 2007,it is found that there are two peaks for the average diurnal variations of the scattering coefficient of aerosols which can be seen at 06：00 BT and 22：00 BT,with values of 508.5 and 431.4 Mm~（-1）.The scattering coefficient is usually higher in winter than that in autumn.The average scattering coefficients are 588.8 Mm~（-1） in fog days,403.7 Mm~（-1） in haze days,and 172.5 Mm~（-1） in fine days. Therefore,the average scattering coefficient is the highest in fog days,while the lowest in fine days.The aerosol scattering coefficient varies obviously in gale weather and dust weather.Before wind speed increases the scattering coefficient is higher,and it decreases in gale weather and dust weather.Diurnal change of the PM_（2.5） mass concentrations accords with the daily change of the scattering coefficient.A good correlation between scattering coefficient and PM_（2.5） mass concentration can be found with a high coefficient of 0.78.%通过对天津市区2006年9月至2007年2月期间散射系数进行统计分析,得出天津市区秋冬季气溶胶散射系数特征：散射系数小时平均值变化范围在100～10000 Mm~（-1）,日变化呈典型双峰形,峰值出现在早6时和晚22时,散射系数分别为508.5和431.4 Mm。冬季散射系数要高于秋季。雾日、霾日和晴天时的平均散射系数分别为588.8,403.7和172.5Mm,雾日的散射系数最大,晴天的散射系数最小。细粒子PM_（2.5）浓度日变化与散射系数日变化曲线非常接近,两者呈正相关,相关系数达到0.78。出现大风扬沙天气时散射系数变化剧烈,PM_（10）浓度出现高值,而散射系数却降低,扬沙天气导致空气中的大粒子浓度增加,当PM_（10）质量浓度表现为高值时,散射系数并没有表现为高值。