Effects of relative humidity on aerosol light scattering: results from different European sites
Effects of relative humidity on aerosol light scattering: results from different European sites
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DOI：
10.5194/acp-13-10609-2013
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发表时间：
2013-01-01
影响因子：
6.3
通讯作者：
Baltensperger, U.
中科院分区：
文献类型：
--
作者：
Zieger, P.;Fierz-Schmidhauser, R.;Baltensperger, U.
本研究通过比较来自欧洲五个地点的测量结果，描述了气溶胶水吸收对气溶胶粒子光散射系数（sigma（sp））的影响：位于瑞士阿尔卑斯山海拔3580 m的少女峰;位于北极斯匹次卑尔根岛的Ny-angstrom lesund;爱尔兰的沿海站点Mace Head;荷兰的农村站点Cabauw;以及德国东部的区域背景站点Melpitz。这些地点是根据该地点通常遇到的气溶胶类型选择的。散射增强因子f（RH，lambda）是描述水分吸收对颗粒光散射影响的关键参数。它被定义为在一定相对湿度（RH）和波长λ下的σ（sp）（RH）除以其干燥值。f（RH）在五个站点变化很大，从非常低的值f（RH = 85%，λ = 550 nm）约1.28矿物粉尘，并达到3.41北极气溶胶。除了少女峰（由于没有海盐），在所有地点都观察到了滞后行为。封闭研究和米氏模拟表明，大小和化学成分决定的f（RH）的大小。这两个参数也需要成功地预测f（RH）。最后，将测量结果与广泛使用的气溶胶模型OPAC（Hess等人，1998年）。显着的差异，特别是在中间相对湿度范围，这些主要是由于不适当的实施吸湿增长的OPAC模型。从最近的文献值的吸湿增长的替代导致了OPAC模型的明显改善。
The effect of aerosol water uptake on the aerosol particle light scattering coefficient (sigma(sp)) is described in this study by comparing measurements from five European sites: the Jungfraujoch, located in the Swiss Alps at 3580 m a.s.l.; Ny-angstrom lesund, located on Spitsbergen in the Arctic; Mace Head, a coastal site in Ireland; Cabauw, a rural site in the Netherlands; and Melpitz, a regional background site in Eastern Germany. These sites were selected according to the aerosol type usually encountered at that location. The scattering enhancement factor f(RH, lambda) is the key parameter to describe the effect of water uptake on the particle light scattering. It is defined as the sigma(sp)(RH) at a certain relative humidity (RH) and wavelength lambda divided by its dry value. f(RH) at the five sites varied widely, starting at very low values of f(RH = 85%, lambda = 550 nm) around 1.28 for mineral dust, and reaching up to 3.41 for Arctic aerosol. Hysteresis behavior was observed at all sites except at the Jungfraujoch (due to the absence of sea salt). Closure studies and Mie simulations showed that both size and chemical composition determine the magnitude of f(RH). Both parameters are also needed to successfully predict f(RH). Finally, the measurement results were compared to the widely used aerosol model, OPAC (Hess et al., 1998). Significant discrepancies were seen, especially at intermediate RH ranges; these were mainly attributed to inappropriate implementation of hygroscopic growth in the OPAC model. Replacement of the hygroscopic growth with values from the recent literature resulted in a clear improvement of the OPAC model.