乌鲁木齐冬春季气溶胶散射吸收特性的差异性及其影响因素

Scattering/absorption Properties of Aerosol and Its Affecting Factors over Urumqi in Spring and Winter

采用积分式浑浊度仪,于2012年1月和5月在乌鲁木齐对气溶胶的散射和吸收系数进行了连续观测,分析冬、春季气溶胶散射和吸收系数的变化趋势,同时,结合同期的相关气象资料和污染物浓度,对变化特征进行了讨论。结果表明:冬、春季气溶胶的散射、吸收系数具有相同的变化趋势,总体上呈现出"W"型;冬季散射、吸收系数分别是春季的10～20倍和5～10倍,说明大气气溶胶的消光作用主要以散射为主。相对湿度(RH)和风速与散射、吸收系数具有显著相关性,污染物浓度和散射吸收系数同样具有显著相关性,其中PM10和NO2对散射系数的影响大于吸收系数,而SO2则对吸收系数的影响较大,反映出不同污染物对气溶胶的散射吸收系数存在差异。

The serious air pollution in Urumqi is caused by the special hill and valley terrains,irrational energy structure and increase of the consumption of heating energy in winter,which intensify the environmental problems.Even in the better environment,people still feel that the city is being shrouded by＂black fog＂. The present study investigated one of the important factors,i. e. the impact of atmospheric aerosols on light. Aiming at revealing the different periods of aerosols affecting visible light,the integrating nephelometer was used to observe the scattering and absorption coefficients of aerosols during the period from January to May 2012. The variations of aerosol scattering and absorption coefficients in winter and spring were analyzed based on the meteorological and pollutant concentration data. The results showed that the change trends of scattering and absorption coefficients in winter and spring were similar,and their curves were W-shaped. The maximal values of scattering and absorbing coefficients in winter and spring were 1 210 Mm- 1,244 Mm- 1,95 Mm- 1and 42 Mm- 1respectively. Moreover,the scattering and absorbing coefficients in winter were 10- 20 and 5- 10 times of that in spring. The results indicated that the extinction of aerosols was mainly depended on scatting. There was a significant correlation between the relative humidity and wind speed and the scattering and absorbing coefficients. The reason was that the increase of air relative humidity helped the aerosol condensation and the increase of aerosol particle size. Wind speed had a positive effect on the scattering and absorption of aerosols,and it also played an important role in concentration reduction and dispersion of pollutants. There was a significant correlation between pollutant concentration and scattering and absorption coefficients,and the effect of PM10and NO2on the scattering coefficient was higher than that of absorbing coefficient. The results indicated that the contribution of PM10to the scattering coefficient was higher than that to the absorption coefficient in north China. SO2and NO2affected significantly the scattering and absorbing coefficients of aerosols. It could be conclude that the effects of different pollutants on the scattering and absorption coefficients of aerosols were different.