Global climate signals and equatorial SST variability in the Indian, Pacific and Atlantic oceans during the 20th century

Abstract

Oceanic global and individual basin (i.e., Indian, Pacific and Atlantic oceans) sea surface temperature (SST) and sea level pressure (SLP) are analyzed jointly, using MTM/SVD technique. Besides global and individual secular variability, differences in low‐frequency climate signals are evidenced: that is, an inter‐decadal signal dominates in the Indian and Pacific oceans, while a quasi‐decadal signal dominates in the Pacific and Atlantic oceans. Two inter‐annual global and individual climate signals dominate: i.e., ENSO and quasi‐biennial (QB). Moreover, significant correlations are found between three known equatorial SST indices (i.e., IO1 in Indian Ocean, NINO3 in Pacific Ocean, and ATL2 in Atlantic Ocean), and SST time‐series obtained by summing‐up only global lead‐frequency signals identified here: i.e., 0.74, 0.82, and 0.56 respectively. These results should help improving long‐term climate numerical forecasts and mitigating societal impacts by using observed specific equatorial SSTs time‐series, in a climate change context.