Multi- and quasi-decadal variations of sea surface temperature in the North Atlantic

Abstract

The multi- and quasi-decadal variabilities of the sea surface temperature (SST) anomaly over the North Atlantic are investigated by means of two-dimensional propagating CEOF. Forty-six years of the COADS SST dataset from 1947 to 1992 are used. After removing the monthly climatology and four-year low-pass filtering the SST anomaly is submitted to CEOF. The total variance of the three largest modes accounts for 87.0% of the total variance. Mode 1 is a very slow oscillation with an approximate 42-yr period and has basinwide spatial evolution, with alternate warm and cold anomalies appearing off Newfoundland and migrating northward until they disappear south of Greenland. The center of action of the anomalies both occur in the vicinity of the Labrador Sea, Newfoundland, and south of Greenland where deep-water formation takes place. Mode 2 + 3 is a quasi-decadal fluctuation with an approximate 14-yr period. Mode 2 + 3 contains quasi-decadal timescales with alternating warm and cold anomalies propagating from the Labrador Sea eastward following the North Atlantic Current and the subpolar gyre.