Air-mass movement and sulphate concentrations on the South African Highveld during August 1987

A well-established interaction exists between the sequence of synoptic weather events characteristic of the southern African subcontinent, the air-mass movement and sulphate concentrations on the South African Highveld. Observations indicate that a sulphate reservoir is created on the Highveld, which can persist for several weeks and affect the sulphate levels on the surface and on the escarpment. Peak sulphate values recorded at the escarpment (> 70 mu g m super(-3) per 24 h) are about one magnitude larger than those on the Highveld, and can be interpreted as being caused by the passage of troughs south of the subcontinent which are closely followed by bud-off anticyclones.