Aerosol loading, hotspot contributions, and climatic interactions across West African climate zones and adjacent regions of Chad and Cameroon

Abstract

This study evaluates aerosol concentration variations (ACV) and their associations with climatic parameters across five West African zones and Central Africa, using 16 years (2008–2023) of satellite data from NASA’s Giovanni platform (MODIS, MERRA-2, AIRS, GPCPMON, GLDAS, and MISR). Central Africa were included because of their geographical continuity with the West Africa. Aerosol metrics (Aerosol Optical Depth [AOD], fine Particulate Matter [PM2.5], Black Carbon [BC], Organic Carbon [OC]) and climatic variables were analyzed using correlation heatmaps, scatter plots, and multiple linear regression. Results show a strong positive correlation between AOD temperature (up to r = 0.74 in the Sudanian zone) and negative associations with precipitation (-0.67 in Sudanian; -0.63 in Sahara). Seasonal peaks varied by zone: Dust-driven in the arid north (Araouane, Mali: 0.74 in June; Fada N’gourma, Burkina Faso: 0.80 in March) and biomass-burning February-driven in the Sudanian belt (Kano, Nigeria: 1.35 in February), and urban-industrial in the humid south (Lagos, Nigeria: 1.07 in). Chad, Abeche and Moussoro show late dry-season peaks (0.66–0.76), while Cameroon (Douala, Limbe, Buea) exhibits moderate but persistent AOD (∼0.87). A regional maximum occurred in 2015, with zonal annual mean of 0.4412 in the Sahara, 0.4921 in the Sahel, 0.6134 in the Sudanian, 0.5510 in the Guinean, and 0.5847 in the Coastal zones. %RAOD identified dominant hotspots, including Araouane (17.11% in 2018), Fada N’gourma (18.48% in 2020), Kano (16.48% in 2020), and Lagos (17.06% in 2009; 16.66% in 2023). These patterns confirm a north-south aerosol gradient consistent across West Africa and adjacent regions.