Aerosol distribution in the northern Gulf of Guinea : local anthropogenic sources, long-range transport, and the role of coastal shallow circulations

Show simple item record Flamant, Cyrille Deroubaix, Adrien Chazette, Patrick Brito, Joel Gaetani, Marco Knippertz, Peter Fink, Andreas H. de Coetlogon, Gaelle Menut, Laurent Colomb, Aurelie Denjean, Cyrielle Meynadier, Remi Rosenberg, Philip Dupuy, Regis Dominutti, Pamela Duplissy, Jonathan Bourrianne, Thierry Schwarzenboeck, Alfons Ramonet, Michel Totems, Julien 2018-09-20T13:48:01Z 2018-09-20T13:48:01Z 2018-08-27
dc.identifier.citation Flamant , C , Deroubaix , A , Chazette , P , Brito , J , Gaetani , M , Knippertz , P , Fink , A H , de Coetlogon , G , Menut , L , Colomb , A , Denjean , C , Meynadier , R , Rosenberg , P , Dupuy , R , Dominutti , P , Duplissy , J , Bourrianne , T , Schwarzenboeck , A , Ramonet , M & Totems , J 2018 , ' Aerosol distribution in the northern Gulf of Guinea : local anthropogenic sources, long-range transport, and the role of coastal shallow circulations ' , Atmospheric Chemistry and Physics , vol. 18 , no. 16 , pp. 12363-12389 .
dc.identifier.other PURE: 115724861
dc.identifier.other PURE UUID: 75642d07-ad6e-4d4f-baca-f0702989b8ac
dc.identifier.other WOS: 000442775100003
dc.identifier.other Scopus: 85052753735
dc.description.abstract The complex vertical distribution of aerosols over coastal southernWest Africa (SWA) is investigated using airborne observations and numerical simulations. Observations were gathered on 2 July 2016 offshore of Ghana and Togo, during the field phase of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa project. This was the only flight conducted over the ocean during which a downward-looking lidar was operational. The aerosol loading in the lower troposphere includes emissions from coastal cities (Accra, Lome, Cotonou, and Lagos) as well as biomass burning aerosol and dust associated with long-range transport from central Africa and the Sahara, respectively. Our results indicate that the aerosol distribution on this day is impacted by subsidence associated with zonal and meridional regional-scale overturning circulations associated with the land-sea surface temperature contrast and orography over Ghana and Togo, as typically observed on hot, cloud-free summer days such as 2 July 2016. Furthermore, we show that the zonal circulation evidenced on 2 July is a persistent feature over the Gulf of Guinea during July 2016. Numerical tracer re-lease experiments highlight the dominance of aged emissions from Accra on the observed pollution plume loadings over the ocean, in the area of aircraft operation. The contribution of aged emission from Lome and Cotonou is also evident above the marine boundary layer. Given the general direction of the monsoon flow, the tracer experiments indicate no contribution from Lagos emissions to the atmospheric composition of the area west of Cotonou, where our airborne observations were gathered. The tracer plume does not extend very far south over the ocean (i.e. less than 100 km from Accra), mostly because emissions are transported northeastward near the surface over land and westward above the marine atmospheric boundary layer. The latter is possible due to interactions between the monsoon flow, complex terrain, and land-sea breeze systems, which support the vertical mixing of the urban pollution. This work sheds light on the complex - and to date undocumented - mechanisms by which coastal shallow circulations can distribute atmospheric pollutants over the densely populated SWA region. en
dc.format.extent 27
dc.language.iso eng
dc.relation.ispartof Atmospheric Chemistry and Physics
dc.rights cc_by
dc.rights.uri info:eu-repo/semantics/openAccess
dc.subject WEST-AFRICA
dc.subject DIURNAL CYCLE
dc.subject AIR-POLLUTION
dc.subject DYNAMICS
dc.subject SYSTEM
dc.subject 1172 Environmental sciences
dc.subject 116 Chemical sciences
dc.subject 114 Physical sciences
dc.title Aerosol distribution in the northern Gulf of Guinea : local anthropogenic sources, long-range transport, and the role of coastal shallow circulations en
dc.type Article
dc.contributor.organization Helsinki Institute of Physics
dc.contributor.organization Polar and arctic atmospheric research (PANDA)
dc.description.reviewstatus Peer reviewed
dc.relation.issn 1680-7316
dc.rights.accesslevel openAccess
dc.type.version publishedVersion

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