Remote biomass burning dominates southern West African air pollution during the monsoon

• Published in: Atmospheric chemistry and physics Vol. 19; no. 24; pp. 15217 - 15234
• Main Authors: Haslett, Sophie L, Taylor, Jonathan W, Evans, Mathew, Morris, Eleanor, Vogel, Bernhard, Dajuma, Alima, Brito, Joel, Batenburg, Anneke M, Borrmann, Stephan, Schneider, Johannes, Schulz, Christiane, Denjean, Cyrielle, Bourrianne, Thierry, Knippertz, Peter, Dupuy, Régis, Schwarzenböck, Alfons, Sauer, Daniel, Flamant, Cyrille, Dorsey, James, Crawford, Ian, Coe, Hugh
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 16.12.2019; European Geosciences Union; Copernicus Publications
• Subjects: Accumulation; Aerosol concentrations; Aerosol properties; Aerosols; African monsoon; Agricultural land; Air masses; Air pollution; Aircraft; Analysis; Anthropogenic factors; Art exhibitions; Art exhibits; Atmosphere; Atmospheric and Oceanic Physics; Atmospheric models; Biomass; Biomass burning; Biomass burning plumes; Burning; Chemical properties; Chemicophysical properties; Cities; Cities and towns; Cloud droplet concentration; Cloud properties; Clouds; Clouds (Meteorology); Computer simulation; Consortia; Emissions; Environmental aspects; Environmental policy; Environmental Sciences; Gases; Human influences; Monsoons; Oceans; Organic chemistry; Outflow; Physics; Plumes; Pollution; Precipitation (Meteorology); Small-scale models; Smoke; Smoke plumes; Trace gases; Tropical climate; Upstream; Wind; United States > US; West Africa; Atlantic Ocean
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-19-15217-2019

Vast stretches of agricultural land in southern and central Africa are burnt between June and September each year, which releases large quantities of aerosol into the atmosphere. The resulting smoke plumes are carried west over the Atlantic Ocean at altitudes between 2 and 4 km. As only limited observational data in West Africa have existed until now, whether this pollution has an impact at lower altitudes has remained unclear. The Dynamics-aerosol-chemistry-cloud interactions in West Africa (DACCIWA) aircraft campaign took place in southern West Africa during June and July 2016, with the aim of observing gas and aerosol properties in the region in order to assess anthropogenic and other influences on the atmosphere. As a result, the large and growing emissions from the coastal cities are overlaid on an already substantial aerosol background. Simulations using COSMO-ART show that cloud droplet number concentrations can increase by up to 27 % as a result of transported biomass burning aerosol. On a regional scale this renders cloud properties and precipitation less sensitive to future increases in anthropogenic emissions. In addition, such high background loadings will lead to greater pollution exposure for the large and growing population in southern West Africa. These results emphasise the importance of including aerosol from across country borders in the development of air pollution policies and interventions in regions such as West Africa.