Aerosol climatology over South Africa based on 10 years of Multiangle Imaging Spectroradiometer (MISR) data

Abstract

In this paper, we present a detailed study of the spatial and seasonal aerosol climatology
\nover South Africa (SA), based on Multiangle Imaging Spectroradiometer (MISR) data.
\nWe have used 10 years (2000–2009) of MISR monthly mean aerosol extinction (text),
\nabsorption (ta) optical depths at 558 nm, Angstrom exponents in visible (VIS; 446–672 nm)
\nand near‐infrared (NIR; 672–866 nm) spectral bands, and the extracted spectral curvature.
\nThe study has shown that, in terms of aerosol load level spatial variation, SA can be classified
\ninto three parts: the upper, central, and lower, which illustrate high, medium, and low
\naerosol loadings, respectively. The results for the three parts of SA are presented in detail.
\nThe prevailing sources of aerosols are different in each part of SA. The lower part is
\ndominated by the air mass transport from the surrounding marine environment and other
\nSA or neighboring regions, while the central and upper parts are loaded through windablated
\nmineral dust and local anthropogenic activities. During the biomass burning seasons
\n(July–September), the central part of SA is more affected than the rest of SA by the biomassburning
\naerosols (based on ta, ∼20% higher than the rest of SA). In alignment with the
\nobserved higher values of text, aerosol size distributions were found to be highly variable
\nin the upper part of SA, which is due to the high population and the industrial/mining/
\nagricultural activities in this area.