Quasi-Decadal Variability in the Atlantic Basin Involving Tropics–Midlatitudes and Ocean–Atmosphere Interactions

Observational data are used to emphasise a 5- to 7-yr lag between the main modes of variability in the midlatitudes and in the Tropics. Considering this finding a mechanism for quasidecadal variability based on Tropics–midlatitudes and ocean–atmosphere interaction is described. It appears that the signal associated with the SST anomalies in the northern region of the tropical Atlantic is transferred in midlatitudes through the atmosphere and it will modify the thermal conditions of the ocean upper layers. In 5–7 years, thermal conditions will affect the SST anomalies in the northern Tropics reversing their sign. The results suggest that the Tropics get a negative feedback from midlatitudes so that the Tropics–midlatitudes system is capable of generating an oscillatory mode.