Examining interannual variability in West Africa from the NCEP reanalyses and the CCM3 for the period of 1979-1993

The mean climate states and interannual variability of the Community Climate Model Version 3.6 (CCM3) is compared to the NCEP reanalyses during the period of 1979-1993. Simulations using climatological SSTs and observed SSTs (1979-1993) are used to investigate interannual variability during a period when below normal rainfall and anomalous atmospheric 200 and 700 mb winds are common over much of West Africa. The CCM3 does captures the north-south gradient of mean summer JJA rainy season precipitation but amounts are underestimated in the Guinea Highlands and near the Gulf of Guinea. The persistent pattern of drier conditions during the 1979-1993 rainy season over West Africa is not captured in the CCM3, but anomalous 200 mb winds are captured during some of the seasons similar to the NCEP reanalyses. The inability to capture interannual variability of precipitation rest with mesoscale convective systems, which the GCM cannot capture. However, output from the CCM3 can be used to drive a regional climate model at the lateral boundaries which may provide further insights on interannual variability.