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Climatological Analysis of Aerosols Optical Properties by Airborne Sensors and in Situ Measurements in West Africa: Case of the Sahelian Zone

This paper deals with the climatology of aerosols in West Africa based on sa- tellite and in situ measurements between 2001 and 2016 and covers four sites in the Sahelian zone. There are indeed Banizoumbou (13.541 ?N, 02.665 ?E), Cinzana (13.278 ?N, 05.934 ?W), Dakar (14.394 ?N, 16.959 ?W) and Ouaga- dougou (12.20 ?N, 1.40 ?W) located respectively in Niger, Mali, Senegal and Burkina Faso. Thus, an intercomparison between the satellite observations and the in situ measurements shows a good correlation between MODIS and AERONET with a correlation coefficient R = 0.86 at Cinzana, R = 0.85 at Ba- nizounbou, R = 0.84 at Ouagadougou and a low correlation coefficient R = 0.66 calculated on the Dakar site. Like MODIS, SeaWiFS shows a very good correspondence with measurements of the ground photometer especially for Banizoumbou (R = 0.89), Cinzana (R = 0.88) and Dakar (R = 0.75) followed by a low correlation coefficient calculated on the Ouagadougou site (R = 0.64). The performance of these airborne sensors is also corroborated by the calcu- lation of root mean square error (RMSE) and the mean absolute error (MAE). Following this validation, a climatological analysis based on aerosol optical depth (AOD) shows the seasonality of aerosols in West Africa strongly influ- enced by the climate dynamics illustrated by the MERRA model reanalysis. This seasonal spatial distribution of aerosols justifies the temporal variability of the particles observed at the different sites in the Sahel. In addition, a com- bined analysis of AOD and Angstrom coefficient indicates the aerosol period in the Sahel in spring (March-April-May) and summer (June-July-August). However, these aerosols are strongly dominated by desert dust whose main sources are located north in the Sahara and Sahel.

Auteur(s) : Nébon Bado, Adama Ouédraogo, Hassime Guengané, Thierry Sikoudouin Maurice Ky, Serge Dimitri Bazyomo, Bruno Korgo, Mamadou Simina Dramé, Saidou Moustap
Pages : 118-135
Année de publication : 2019
Revue : Open Journal of Air Pollution
N° de volume : 8
Type : Article
Mise en ligne par : SALL Saïdou Moustapha