The structure of daily austral summer rainfall variability over southern Africa and the Southwest Indian Ocean has been analysed objectively by calculating empirical orthogonal functions of daily rainfall over both land and ocean. Daily rainfall is calculated from recently released satellite products from the International Satellite Cloud Climatology Programme (ISCCP). Tropical-temperate links are the main mode of daily rainfall variability in the region for each of the summer months of November to March. These links are orientated northwest to southeast with a locus of activity over Zambia, Zimbabwe and Mozambique, extending to the Southwest Indian Ocean near 40°S and 50°E. In all months except February, these links have a dipole structure such that enhanced (suppressed) convection over the northwest to southeast-orientated band described above is associated with suppressed (enhanced) convection over a similarly orientated band with maxima over Namibia, South Africa and the Southern Ocean near 35°S and 30°E. Events characterised by such tropical-temperate connections are relatively infrequent and exhibit marked interannual variability. Average rainfall anomalies associated with composites of the major extreme temperate-tropical events peak at 8-10 mm per day in each month. The proportional contribution of this small number of extreme events to total rainfall is substantial, and tends to be highest over ocean regions.
