A GCM Study of the Teleconnections between the Continental Climate of Africa and Global Sea Surface Temperature Anomalies

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Abstract
In this case study the role of global SST anomaly forcing in promoting the extreme climatic conditions that prevailed in Africa during the years of 1950 and 1973 is examined. In 1950 abundant rainfall was observed over tropical Africa, particularly over the Sahel and Southern Africa. By contrast, in 1973, this rainfall anomaly pattern was characterized by the opposite phase, with most of the continent experiencing severe droughts. The primary research vehicle in this investigation is the standard version of the NCAR CCMI GCM with horizontal resolution of rhomboidal spectral truncation at wavenumber 15 (R15). Two separate 10-yr simulations based on the 1950 and 1973 observed sea surface temperature (SST) have been performed. The empirical orthogonal functions method is employed to isolate the annual cycle harmonies in the data and also to remove statistical noise. The filtered seasonal rainfall fields for the model and the observations are compared to investigate the response of the African contin... Abstract In this case study the role of global SST anomaly forcing in promoting the extreme climatic conditions that prevailed in Africa during the years of 1950 and 1973 is examined. In 1950 abundant rainfall was observed over tropical Africa, particularly over the Sahel and Southern Africa. By contrast, in 1973, this rainfall anomaly pattern was characterized by the opposite phase, with most of the continent experiencing severe droughts. The primary research vehicle in this investigation is the standard version of the NCAR CCMI GCM with horizontal resolution of rhomboidal spectral truncation at wavenumber 15 (R15). Two separate 10-yr simulations based on the 1950 and 1973 observed sea surface temperature (SST) have been performed. The empirical orthogonal functions method is employed to isolate the annual cycle harmonies in the data and also to remove statistical noise. The filtered seasonal rainfall fields for the model and the observations are compared to investigate the response of the African contin...