Interannual to Decadal Variability in the Tropical Atlantic

Analyses of annual mean sea surface temperatures (SST) from observations for the period 1903-94 and four different general circulation models (GCMs) were conducted. The two dominant EOFs of all datasets are characterized by two patterns, which are centered in the trade wind zones, at roughly 15 degrees N and 15 degrees S, respectively. The two patterns are uncorrelated at any lag and the time spectra of the corresponding principle components are consistent with red noise. The SST variability is strongly correlated with wind stress anomalies in the trade wind zones. The correlations between the wind stress and the SST, as well as the correlation between the net heat flux and the SST anomalies are consistent with the assumption that the variability of the upper tropical Atlantic Ocean is forced by the atmosphere. Dynamic feedbacks of the tropical Atlantic Ocean are less important. The variability in the trade wind zones shows a weak correlation with the ENSO mode in the tropical Pacific.