Climate variability in central equatorial Africa: Influence from the Atlantic sector

Abstract

We document a strong teleconnection between Central Equatorial African (CEA) rainfall (and Congo River discharge) and the large-scale circulation over the North Atlantic, throughout the boreal winter/spring season. Positive rainfall anomalies over CEA (at interannual and multiannual timescales) are related to anomalous westerly mid-tropospheric zonal winds over the CEA/Atlantic region. These anomalies appear to be part of a coherent structure of zonal wind anomalies extending to the polar regions of the North Atlantic, similar to that associated with the NAO pattern. Idealised model simulations suggest that at least over the tropical and subtropical latitudes of the Atlantic/African sector such a signal may be associated with SST forcing from the Tropical North Atlantic (TNA) region. We conclude that TNA SSTs may force these circulation anomalies over CEA at multi-annual timescales but at interannual timescales they may be relatively independent of TNA SSTs. Copyright 2004 by the American Geophysical Union.