Simulating midsummer climate over southern Africa using a nested regional climate model

The Commonwealth Scientific and Industrial Research Organisation (CSIRO) Di vision of Atmospheric Research limited area model (DARLAM) is used to simul ate midsummer (January) climate over southern Africa. Using a one-way nesti ng procedure, lateral boundary and initial conditions are supplied by the C SIRO nine-level Mark 2 general circulation model (GCM), CSIRO9. In general, the DARLAM results are improved in comparison with those from CSIRO9, alth ough certain deficiencies in the GCM climatology over southern Africa are a lso present in the nested model results. DARLAM captures the spatial patter n of observed rainfall and interannual rainfall variability over the region as a whole more accurately than CSIRO9. Over most parts of the subcontinen t, interannual rainfall variability simulated by DARLAM is not significantl y different from observations. Over the steep escarpment region of south-ea st South Africa, DARLAM simulates more rainfall than CSIRO9 and significant ly more rainfall than observed. Over Madagascar, DARLAM simulates more rain fall than CSIRO9, but less than observed, and interannual variability is al so significantly less than the observed variability.