Revisiting the Great Salinity Anomaly of the 1970s

  • 4 November 2020
Revisiting the Great Salinity Anomaly of the 1970s

The Great Salinity Anomaly of the 1970s is the most dramatic decadal-scale, low salinity event observed in the subpolar North Atlantic. Originally the event was thought to be caused by a dramatic influx of freshwater into the region. Researchers, funded by both CPO’s Climate Variability & Predictability (CVP) program and the Department of Energy (DOE), used simulation modeling to offer an alternative view of the Great Salinity Anomaly and possible drivers of the shutdown of the Labrador Sea deep convection.

The North Atlantic Oscillation (NAO) and extreme Fram Strait sea-ice export (FSSIE) are two possible drivers. Surprisingly, researchers found that the reduced surface heat flux (driven by the negative phase NAO) played a bigger role in shutting down Labrador Sea convection than previously thought, rather than the role of Fram Strait sea-ice export (i.e., freshwater) during this low-salinity event.

These results, published in the Journal of Climate, are challenging long-standing thoughts on the development of the 1970's low salinity event in the North Atlantic/Labrador Sea. These findings also have implications for Atlantic teleconnections, given an anticipated increase in freshwater input from Greenland and Arctic due to a warming climate in the future.

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