Publicações

The dominant modes of coupled ocean-atmosphere variability of the Tropical Atlantic are investigated using observational data, focusing on the cold tongue mode. The seasonal evolution and interannual variability of each mode is obtained from a joint EOF analysis of the three elements of the Bjerknes feedback, using wind speed in the western basin, and sea surface temperature (SST) and depth of the 20C isotherm from the easternmost Tropical Atlantic. Results agree with previous studies, confirming the robustness and seasonality of the positive Bjerknes feedback. The analysis reveals a dominant mode of variability remotely forced by El Nino–Southern Oscillation (ENSO) after 0–12 months, with smaller amplitude due to a limited feedback between SST and the wind speed. The second mode represents the local ocean–atmosphere interaction of the Tropical Atlantic basin, and is characterized by a strong positive feedback and a larger amplitude. Both modes are stronger during boreal summer.