气候变化领域集成服务门户(CCPortal): Experimental study of the aerosol impact on fog microphysics

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DOI	10.5194/acp-19-4323-2019
	Experimental study of the aerosol impact on fog microphysics
	Mazoyer M.; Burnet F.; Denjean C.; Roberts G.C.; Haeffelin M.; Dupont J.-C.; Elias T.
发表日期	2019
ISSN	16807316
起始页码	4323
结束页码	4344
卷号	19 期号:7
英文摘要	Comprehensive field campaigns dedicated to fog life cycle observation were conducted during the winters of 2010.2013 at the Instrumented Site for Atmospheric Remote Sensing Research (SIRTA) observatory in a suburb of Paris. In order to document their properties, in situ microphysical measurements collected during 23 fog events induced by both radiative cooling and stratus lowering are examined here. They reveal large variability in number, concentration and size of both aerosol background before the fog onset and fog droplets according to the different cases. The objective of this paper is to evaluate the impact of aerosol particles on the fog microphysics. To derive an accurate estimation of the actual activated fog droplet number concentration Nact, we determine the hygroscopicity parameter k, the dry and the wet critical diameter and the critical supersaturation for each case by using an iterative procedure based on the k-Kohler theory that combines cloud condensation nuclei (CCN), dry particle and droplet size distribution measurements. Our study reveals low values of the derived critical supersaturation occurring in fog with a median of 0.043 %. Consequently, the median dry and wet activation diameters are 0.39 and 3.79 μm, respectively, leading to a minor fraction of the aerosol population activated into droplets. The corresponding Nact values are low, with median concentrations of 53.5 and 111 cm-3 within the 75th percentile. The activated fraction of aerosols exhibits remarkably low correlation with k values, which reflects the chemical composition of the aerosols. On the contrary, the activated fraction exhibits a strong correlation with the inferred critical diameter throughout the field campaigns. This suggests that the variability in the activated fraction is mostly driven by particle size, while variations in aerosol composition are of secondary importance. Moreover, our analysis suggests that the supersaturation reached in fog could be lowered by the aerosol number concentration, which could contribute to the sink term of water vapor during the radiative cooling. Although radiative fogs are usually associated with higher aerosol loading than stratus-lowering events, our analysis also reveals that the activated fraction at the beginning of the event is similar for both types of fog. However, the evolution of the droplet concentration during the fog life cycle shows significant differences between both types of fog. This work demonstrates that an accurate calculation of supersaturation is required to provide a realistic representation of fog microphysical properties in numerical models. © 2019 Author(s).
语种	英语
scopus关键词	aerosol; cooling; experimental study; fog; life cycle analysis; remote sensing; suburban area; winter; France; Ile de France; Paris; Ville de Paris
来源期刊	Atmospheric Chemistry and Physics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/144515
作者单位	CNRM, Université de Toulouse, Méteó-France, CNRS, Toulouse, France; Institut Pierre Simon Laplace, UVSQ, Palaiseau, France; HYGEOS, Lille, France
推荐引用方式 GB/T 7714	Mazoyer M.,Burnet F.,Denjean C.,et al. Experimental study of the aerosol impact on fog microphysics[J],2019,19(7).
APA	Mazoyer M..,Burnet F..,Denjean C..,Roberts G.C..,Haeffelin M..,...&Elias T..(2019).Experimental study of the aerosol impact on fog microphysics.Atmospheric Chemistry and Physics,19(7).
MLA	Mazoyer M.,et al."Experimental study of the aerosol impact on fog microphysics".Atmospheric Chemistry and Physics 19.7(2019).