| Summary: | The long-term North Atlantic Cold Anomaly (Cold Blob) was largely the consequence of three major episodes of low sea surface temperature (SST) in the subpolar North Atlantic in 1972-74, 1984-85 and 1991-94. Each of these episodes correlated with unusually low SST at Flemish Cap (a subsurface island of the Canadian continental shelf 600km east of Newfoundland) and with periods of high sea-ice cover over the deep basin of the Labrador Sea a year earlier. These cold periods at Flemish Cap and the Cold Blob were associated with the advance of sea-ice and icebergs to Flemish Cap, high iceberg counts off the coast of Newfoundland and the appearance of icebergs along the path of the North Atlantic Current (NAC) east of Flemish Cap. Studies of SST anomalies provided evidence for surface connections between Flemish Cap and the CB which utilize part of the NAC pathway. We propose that in the cold periods, residual meltwater from sea-ice and icebergs conveyed in the Labrador Current to Flemish Cap was relayed via the NAC to the subpolar North Atlantic to form the Cold Blob. After 1995, anomalous ice expansion in the Labrador Sea basin greatly diminished, sea-ice and icebergs did not reach Flemish Cap and cold meltwater was no longer transmitted to the subpolar North Atlantic to sustain the Cold Blob. This improved understanding of 20th century meltwater pathways in the North Atlantic may relate to changes in the Atlantic Meridional Overturning Circulation and associated impacts on regional climate in the 21st century.
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