Teleconnections between the northern North Atlantic and the Tropical Atlantic

Abstract

Paleoclimatic reconstructions of variations in rainfall and upwelling in the tropical Cariaco Basin, off Venezuela coast, suggest that meridional displacement of the Intertropical Convergence Zone (ITCZ) is linked to high latitude sea surface temperature (SST) anomalies at different timescales. This study investigates instrumental records in search for covariability between the Cariaco Basin area and the Norwegian Sea. The interannual correlation between the Norwegian Sea SST anomalies and SST elsewhere are similar to the North Atlantic Oscillation (NAO) imprint on the SST in the North Atlantic. This indicates that at these timescales the NAO's atmospheric forcing dominates the air-sea interactions over the North Atlantic. However, they can not fully explain the weak interannual correlations between the SST and sea level pressure (SLP) indices of the Norwegian and Caribbean Seas. At interdecadal timescales the whole Atlantic seems to be dominated by a basin wide spatial pattern of positive correlations, which roughly resembles the Atlantic Multidecadal Oscillation (AMO) spatial pattern. This is believed to describe variations of the thermohaline circulation (THC). The resulting pattern of the Norwegian Sea SST correlated with the SLP elsewhere, both at interannual and interdecadal timescales, is similar to the anomalous SST conditions in the North Atlantic associated with a dipole-like atmospheric circulation, that modifies the air-sea interactions and the THC intensity. Despite some discrepancies with other studies, our results indicate that the interdecadal covariability between the Norwegian and the Caribbean Seas is due to the existence of the THC, and that its strength is modulated by the wind-evaporation mechanism, local processes or remote forcing through an atmospheric teleconnection.