Characteristics of Absorbing and Non-Absorbing Aerosol over South Africa using MODIS and OMI satellite measurements

Abstract

Abstract A study on the spatiotemporal variation of aerosols over South Africa was conducted using MODIS, OMI, MERRA-2 and CALIPSO data from 2004 to 2023. The study showed that absorbing aerosols dominates the aerosol regime in all the study locations while exhibiting seasonal variations. Further to this, aerosols were apportioned from the different sources in each location using HYSPLIT cluster analysis. During the period under consideration, aerosol loading and AAOD were on the increase in almost all the locations and the peak period was during spring (SON) and summer (DJF). This work also showed that diurnally aerosol loading varies extensively at some locations. Consequently, the Kalahari Desert (KD) and Namibian Desert (ND) are the leading sources of dust aerosols in South Africa, especially locations within the northeast and northwestern parts of the country, while industrial emissions and biomass footprints were also observed. Elevated smoke was also observed around the ports and coastlines which is likely emissions from ships docking at the ports. Finally, the study demonstrated that Durban (DBN), Nelspruit (NPT), Cape Town (CPT) and Polokwane (PLK) are the most polluted sites in South Africa and the major aerosol constituents were identified to be elevated smoke and dust in addition to the contribution from marine for DBN. Hence, more than 37% of the aggregated aerosols loading occurred in Durban (DBN), Nelspruit (NPT), and Cape Town (CPT) where absorbing aerosols loading were very conspicuous. This high concentration of aerosols is attributable to the wind regime prevalent around these locations in addition to the socio-economic activities therein.