Study of the relative humidity dependence of aerosol light-scattering in southern Spain
Study of the relative humidity dependence of aerosol light-scattering in southern Spain
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DOI：
10.3402/tellusb.v66.24536
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发表时间：
2014-01
期刊：
影响因子：
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通讯作者：
G. Titos;H. Lyamani;A. Cazorla;M. Sorribas;I. Foyo-Moreno;A. Wiedensohler;L. Alados-Arboledas
中科院分区：
文献类型：
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作者：
G. Titos;H. Lyamani;A. Cazorla;M. Sorribas;I. Foyo-Moreno;A. Wiedensohler;L. Alados-Arboledas
这项调查的重点是气溶胶粒子的吸湿性的表征。在2013年冬季和春季，在西班牙的格拉纳达测量了气溶胶粒子的光学特性。测量的光学性质包括在干燥条件和相对湿度（RH）为85± 10%下的颗粒光吸收系数（σap）和颗粒光散射系数（σsp）。散射增强因子f（RH=85%）在冬季和春季的平均值分别为1.5±0.2和1.6±0.3。高散射增强的情况下，更频繁地在春季运动与27%的f（RH=85%）值高于1.8，而在冬季运动只有8%的数据高于1.8。一个撒哈拉沙尘事件（沙尘暴），这发生在春季运动，其特点是一个大颗粒与低吸湿性占主导地位。对于呼吸更强烈的那一天，计算出平均每日值f（RH=85%）=1.3±0.2。f（RH=85%）日变化曲线在上午和下午交通高峰期出现两个极小值，这是由于黑碳和道路灰尘等非吸湿颗粒物的增加造成的。这是证实了由小值的单次散射的散射和散射的ngstrom指数。F（RH=85%）和颗粒有机物和硫酸盐的分数之间的显着相关性。最后，在气溶胶辐射强迫的环境相对湿度的影响被发现是非常小的，由于环境相对湿度低。对于高RH值，应考虑吸湿效应，因为气溶胶强迫效率从干燥条件下的−13 W/m2变为RH= 85%时的−17 W/m2。
This investigation focuses on the characterisation of the aerosol particle hygroscopicity. Aerosol particle optical properties were measured at Granada, Spain, during winter and spring seasons in 2013. Measured optical properties included particle light-absorption coefficient (σap) and particle light-scattering coefficient (σsp) at dry conditions and at relative humidity (RH) of 85±10%. The scattering enhancement factor, f(RH=85%), had a mean value of 1.5±0.2 and 1.6±0.3 for winter and spring campaigns, respectively. Cases of high scattering enhancement were more frequent during the spring campaign with 27% of the f(RH=85%) values above 1.8, while during the winter campaign only 8% of the data were above 1.8. A Saharan dust event (SDE), which occurred during the spring campaign, was characterised by a predominance of large particles with low hygroscopicity. For the day when the SDE was more intense, a mean daily value of f(RH=85%)=1.3±0.2 was calculated. f(RH=85%) diurnal cycle showed two minima during the morning and afternoon traffic rush hours due to the increase in non-hygroscopic particles such as black carbon and road dust. This was confirmed by small values of the single-scattering albedo and the scattering Ångstrom exponent. A significant correlation between f(RH=85%) and the fraction of particulate organic matter and sulphate was obtained. Finally, the impact of ambient RH in the aerosol radiative forcing was found to be very small due to the low ambient RH. For high RH values, the hygroscopic effect should be taken into account since the aerosol forcing efficiency changed from −13 W/m2 at dry conditions to −17 W/m2 at RH=85%.