Causes and Consequences of the Late 1960s Great Salinity Anomaly

Abstract

The second half of the 20th century showed a series of decadal-scale anomalies of salinity, temperature and sea ice cover in the northern North Atlantic. One pronounced event, the 'great salinity anomaly' (GSA) is observed in the late 1060s and the early 1970s (Dickson et al., 1988). This anomaly can be linked to the sea ice volume out of the Arctic through Fram Strait, which represents a major source of freshwater (Aagaard & Carmack, 1989; Schmith & Hansen, 2003). Increased sea ice export from the Arctic Ocean stabilizes the upper water column in the North Atlantic, diminishes the production of intermediate and deep water masses through ocean convection and can influence the large-scale ocean circulation (Hakkinen, 1999). An important part of sea ice export from the Arctic is forced by specific atmospheric structures (Hilmer et al., 1998; Hakkinen and Geiger, 2000; Cavalieri 2002). These can be parts of coupled ocean-atmosphere modes of climate variability with large-scale projections.