On the. role of the south Atlantic atmospheric circulation in tropical Atlantic variability
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2004 by the American Geophysical Union. One dominant manifestation of tropical Atlantic variability (TAV) takes place in March-April-May in the form of a strong inter-hemispheric sea surface temperature gradient coupled to a cross-equatorial near surface atmospheric flow. The variability of this circulation pattern affects the position of the intertropical convergence zone and the regional climate in the surrounding areas. In this study, we investigated the effect of the South Atlantic atmospheric variability on this phenomenon. We found that southern summer atmospheric variability (and to a lesser extent winter variability) can play a pre-conditioning role in the onset of inter-hemispheric anomalies in the deep tropics during the following austral fall. It does so by inducing a sea surface temperature anomaly in the southern tropics that initiates local thermodynamic air-sea feedbacks. This remote influence of the Southern Hemisphere on TAV is contrasted with the remote influence of El Nio-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO) during austral summer. The results suggest that to fully understand TAV and its predictability it is necessary to consider not only the remote influences from ENSO and NAO, but also the influence from the South Atlantic atmospheric circulation.
