Seasonal and Interannual Variability in Atmospheric Turbidity over South Africa

Aerosols affect climate by attenuating solar radiation and acting as cloud condensation nuclei. Despite their importance in the climate system, our understanding of the time-space variability of aerosols is fragmentary. Measurements and reliable estimates of atmospheric turbidity—the total column amount of aerosol—are scarce in most countries and this is especially true in the Southern Hemisphere. Very little is known about the seasonal, interannual and spatial variability of aerosols over the southern half of the globe. In this paper, we estimate monthly averaged atmospheric turbidity from surface climate data at eight locations in South Africa, regardless of cloud cover. Findings include new estimates of turbidity trends and variability over South Africa. Seasonal trends are evident at many stations, although there is no consistent trend. Over recent decades, turbidity has generally been stable at six of the eight stations. Our methodology can be applied at any location where the requisite climate data are available and, therefore, holds promise for a more complete, and possibly global, climatology of aerosols. Copyright © 2001 Royal Meteorological Society.