The Long Term Spatial-temporal Distribution of Aerosol Optical Depth and Its Associated Atmospheric Circulation Over Southeast Africa.

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Abstract Recent studies have revealed significant impacts of increased concentration of anthropogenic aerosols in the atmosphere to both climate and human health. Southeast Africa is one of the regions where studies related to atmospheric aerosols remain scant, causing high uncertainty in predicting and understanding the impacts of these aerosols to both climate and human health. The present study therefore has investigated the long term spatial-temporal distribution of atmospheric aerosols, trends, its relationship with cloud properties and the associated atmospheric circulation over the region. High concentration of aerosol has been detected during the dry months of September to November (SON) while low during March to May (MAM) and June-July (JJA) seasons in most areas. Highest 550 was recorded in areas with low elevation such as over Lake Malawi, Zambezi valley and along the western coast of the Indian Ocean. The average of the detected concentration is however low as compared to highly polluted regions of the globe. Statistical analyses revealed insignificant change of AOD550 in most areas between 2002 and 2020 time period. The study has also revealed seasonality of aerosol distribution highly influenced by changes in atmospheric circulation. Burning of biomass during dry months such bush fires and burning of crop residues remain the major source of anthropogenic aerosol concentration over Southeast Africa hence needs to be controlled.

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