Chemical evidence of long-range atmospheric transport over southern Africa

[1] Atmospheric stability and many natural and anthropogenic sources lead to the accumulation of aerosols over southern Africa with potential climatic forcing consequences. A trajectory climatology for southern Africa shows that air circulates over the entire region for several days in an anticyclonic type pattern of flow concentrating aerosols and trace gases below 700 or 500 hPa. A long-term, time-resolved, size-fractionated aerosol monitoring site along the locus of one of the main transport routes was established at Ben Macdhui mountain in the eastern Cape (similar to30degreesS, 28degreesE). Chemical data collected from initial samples indicated that distinctive episodes of industrial-related emissions are detected at the site using inorganic fine sulfur as a unique tracer. In addition, two intensive sampling campaigns were undertaken to augment the long-term data set. Emissions from four sources influencing the aerosol content at Ben Macdhui were identified: aeolian dust or soil from the natural landscape, industry, biomass burning, and sea-salt emissions from the marine environment. The industrial aerosols were transported mostly in an anticyclonic recirculation pattern from the Highveld and had a distinct chemical signature. Some industrial emissions were transported from the east between the site and the east coast of South Africa.