3-DIMENSIONAL KINEMATIC TRAJECTORY MODELING OF WATER-VAPOR TRANSPORT OVER SOUTHERN AFRICA

Back and forward kinematic trajectory modelling has been undertaken fo r rain and no-rain days over the central interior of South Africa in m id-summer. No-rain days (rain days) are shown to be characterised by d ry (moist) south-westerly (northerly to north-easterly) flow originati ng over the South Atlantic (tropical Indian) Ocean. Air parcels for tr opical-temperate troughs originate over the tropical Indian Ocean and trace south and south-eastwards across Southern Africa, corresponding closely to the position of the trough-associated cloud band. Trajector y modelling of a cut-off low pressure system reveals tile presence and interaction of a cold, dry, descending conveyor from the south and a warm, moist, ascending conveyor from the north.