济南秋季霾与非霾天气下气溶胶光学性质的观测

应用黑碳仪和积分浊度计于2009年10月11日至11月18日针对济南市大气气溶胶的光学特性进行了观测.结果显示,观测期间霾天气的散射系数和吸收系数及非霾天气的散射系数和吸收系数平均值分别为(582.5±311)Mm-1、(680.2±47.2)Mm-1和(205.7±134.8)Mm-1、(31.0±25.8)Mm-1.霾天气的气溶胶散射系数和吸收系数分别为非霾天气的2.6倍和2.8倍,单词散射反照率(SSA)也高于非霾天气.霾天气中二次气溶胶生成及黑碳气溶胶聚集是改变吸收系数、散射系数和SSA的日变化趋势的重要原因.此外,估算了观测期间及霾和非霾天气中气溶胶的光学厚度(AOD)分别为0.78,1.14和0.47.后向气流轨迹分析显示,非霾天气的气流主要来自于济南的西北至东北方向,运动速度快;而霾天气的所有的气流均来自于济南西南至东南方向,运动速度慢,当气流经过山东南部的火点时加剧了济南市的霾,并严重影响到该地区大气气溶胶的光学性质.

Characteristics of aerosol optical properties at haze and non-haze weather during autumn at Jinan city

A field study was carried out using aethelometer and nephelometer from 11 October to 18 November, 2009 in Jinan. The results show that mean scattering coefficient (Scat.) and absorption coefficient (A.) are (582.5±311) Mm-1 and (680.2±47.2) Mm-1 during hazy day, (205.7±134.8) Mm-1 and (31.0±25.8) Mm-1 during non-hazy days. In particular, Scat. and Abs. on hazy day were 2.6 and 2.8 times higher than those on non-hazy days. Also, single scattering albedo (SSA) also exhibited a higher value on hazy days. Diurnal variations of Scat., A., and SSA should attribute to the formation of secondary aerosols and the accumulation of black carbon on hazy days. Furthermore, the mean values of AOD during the whole period, hazy days, and non-hazy days were 0.78, 1.14, and 0.47, respectively. On basis of the analysis of air mass back trajectories, air masses with high speed came from northwest to northeast of Jinan during the non-haze days, whereas air masses with low speed came from southwest to southeast of Jinan. Therefore, those southerly air masses passed the wildfire spots in south of Shandong province would promote formation of the regional hazes, and changed the optical properties of aerosol particles in Jinan.