气候变化领域集成服务门户(CCPortal): Overview of aerosol optical properties over southern West Africa from DACCIWA aircraft measurements

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DOI	10.5194/acp-20-4735-2020
	Overview of aerosol optical properties over southern West Africa from DACCIWA aircraft measurements
	Denjean C.; Bourrianne T.; Burnet F.; Mallet M.; Maury N.; Colomb A.; Dominutti P.; Brito J.; Dupuy R.; Sellegri K.; Schwarzenboeck A.; Flamant C.; Knippertz P.
发表日期	2020
ISSN	1680-7316
起始页码	4735
结束页码	4756
卷号	20 期号:8
英文摘要	Southern West Africa (SWA) is an African pollution hotspot but a relatively poorly sampled region of the world. We present an overview of in situ aerosol optical measurements collected over SWA in June and July 2016 as part as of the DACCIWA (Dynamics-Aerosol-Chemistry-Clouds Interactions in West Africa) airborne campaign. The aircraft sampled a wide range of air masses, including anthropogenic pollution plumes emitted from the coastal cities, long-range transported biomass burning plumes from central and southern Africa and dust plumes from the Sahara and Sahel region, as well as mixtures of these plumes. The specific objective of this work is to characterize the regional variability of the vertical distribution of aerosol particles and their spectral optical properties (single scattering albedo: SSA, asymmetry parameter, extinction mass efficiency, scattering Ångström exponent and absorption Ångström exponent: AAE). The first findings indicate that aerosol optical properties in the planetary boundary layer were dominated by a widespread and persistent biomass burning loading from the Southern Hemisphere. Despite a strong increase in aerosol number concentration in air masses downwind of urban conglomerations, spectral SSA were comparable to the background and showed signatures of the absorption characteristics of biomass burning aerosols. In the free troposphere, moderately to strongly absorbing aerosol layers, dominated by either dust or biomass burning particles, occurred occasionally. In aerosol layers dominated by mineral dust particles, SSA varied from 0.81 to 0.92 at 550 nm depending on the variable proportion of anthropogenic pollution particles externally mixed with the dust. For the layers dominated by biomass burning particles, aerosol particles were significantly more light absorbing than those previously measured in other areas (e.g. Amazonia, North America), with SSA ranging from 0.71 to 0.77 at 550 nm. The variability of SSA was mainly controlled by variations in aerosol composition rather than in aerosol size distribution. Correspondingly, values of AAE ranged from 0.9 to 1.1, suggesting that lens-coated black carbon particles were the dominant absorber in the visible range for these biomass burning aerosols. Comparison with the literature shows a consistent picture of increasing absorption enhancement of biomass burning aerosol from emission to remote location and underscores that the evolution of SSA occurred a long time after emission. The results presented here build a fundamental basis of knowledge about the aerosol optical properties observed over SWA during the monsoon season and can be used in climate modelling studies and satellite retrievals. In particular and regarding the very high absorbing properties of biomass burning aerosols over SWA, our findings suggest that considering the effect of internal mixing on absorption properties of black carbon particles in climate models should help better assess the direct and semi-direct radiative effects of biomass burning particles.. © 2020 BMJ Publishing Group. All rights reserved.
语种	英语
scopus关键词	aerosol property; air mass; airborne survey; atmospheric plume; atmospheric pollution; biomass burning; in situ measurement; long range transport; Sahara; Sahel [Sub-Saharan Africa]; West Africa
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/247830
作者单位	CNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, France; LaMP, Université de Clermont Auvergne, Clermont-Ferrand, France; LATMOS/IPSL, Sorbonne Université, UVSQ, CNRS, Paris, France; Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany; Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, York, YO10 5DD, United Kingdom; IMT Lille Douai, Université de Lille, SAGE, Lille, France
推荐引用方式 GB/T 7714	Denjean C.,Bourrianne T.,Burnet F.,et al. Overview of aerosol optical properties over southern West Africa from DACCIWA aircraft measurements[J],2020,20(8).
APA	Denjean C..,Bourrianne T..,Burnet F..,Mallet M..,Maury N..,...&Knippertz P..(2020).Overview of aerosol optical properties over southern West Africa from DACCIWA aircraft measurements.ATMOSPHERIC CHEMISTRY AND PHYSICS,20(8).
MLA	Denjean C.,et al."Overview of aerosol optical properties over southern West Africa from DACCIWA aircraft measurements".ATMOSPHERIC CHEMISTRY AND PHYSICS 20.8(2020).