广州中心城区冬季大气气溶胶消光特性观测研究

2013年12月利用广州市大气超级站气溶胶吸收系数、散射系数、污染物及气象观测数据，分析了广州冬季大气消光组成变化及其影响因子。观测期间，黑碳浓度均值为6．98±3．71μg／m^3，气溶胶吸收系数均值为60．04±30．72Mm^-1，气溶胶散射系数均值为363．51±182．18Mm^-1，单次散射反照率均值为0．85±0．04。在总消光系数中气溶胶吸收消光占13％，气溶胶散射消光占81％。气溶胶吸收系数与散射系数日变化均呈双峰结构，这与人类活动和气象条件的改变有关。通过最大频数拟合得到广州冬季气溶胶吸收系数和散射系数本底值分别为32．93Mm^-1和281．82Mm^-1。气溶胶散射系数和吸收系数与PM2.5质量浓度呈线性正相关，与大气能见度呈指数负相关。通过测量气溶胶消光和气体消光分量加和获得的消光系数与能见度仪消光系数变化趋势基本一致，降雨及较高相对湿度对能见度仪消光系数影响较大。

Study of Characteristic of Aerosol Extinction in G uangzhou Urban Area During the Winter

Based on the observational data of aerosol scattering and absorption coefficient,pollutants,and meteorological data at Guangzhou in Dec 2013,characteristics and influencing factors of atmospheric extinction variation were analyzed. The average concentration of BC was 6.98±3.71μg/m^3.The average value of aerosol absorption extinction and scatting extinction was 60.04±30.72Mml and 363.51±182.18Mm^-1 respectively. The single scattering albedo was 0.85±0.04. The aerosol absorption extinction accounted for about 13% and aerosol scatting extinction accounted for about 81% in total extinction coefficient respectively.Daily variation of aerosol scattering and absorption coefficients presented double-peak distributions,which can be attributed to morning and evening rush hours and atmospheric boundary layer diurnal changes. Based on statistical method and lognormal curve fitting analysis, the background level of aerosol absorption extinction and scatting extinction was 32.93Mm^-1 and 281.82Mm^-1 respectively. There was a good linear correlation between aerosol scattering or absorption coefficients and PM2.5 mass concentration and typical negative exponential correlation with the visibility. The sum of observation aerosol extinction coefficient and gas extinction coefficient was consistent with extinction coefficient retrieval from visibility. Extinction coefficient retrieval from visibility has a large variation when relative humidity was higher or during the rainfall.