Arctic Ocean Circulation and Nordic Seas Hydrography: Oceanic and Atmospheric Connections

The Beaufort Gyre, a wind-driven ocean circulation, constitutes a major freshwater reservoir in the Arctic Ocean. The Beaufort High, a semi-permanent high-pressure system, induces anticyclonic winds and Ekman downwelling, corralling available surface freshwater in the gyre. On interannual to decadal timescales, intensification (relaxation) of surface winds results in accumulation (release) of freshwater, modifying the freshwater export to the North Atlantic Ocean. The Arctic Ocean freshwater export is thought to play an important role in determining the stratification of the Nordic Seas. Indeed, the “Great Salinity Anomaly” events of the 1970s-1990s, in which freshwater anomalies followed coherent advection pathways through the subpolar North Atlantic Ocean, may have been induced or augmented by freshwater pulses from the Beaufort Gyre which entered the North Atlantic Ocean through Fram Strait and/or Davis Strait.

On the other hand, recent evidence suggests that the freshwater content variability of the Nordic Seas is closely linked to the salt flux of the Atlantic inflow across the Greenland-Scotland Ridge, which is modulated by the strength of the subpolar gyre circulation. Thus, the role of Arctic freshwater pulses in modifying the stratification of the Nordic Seas may be limited by North Atlantic Ocean dynamics. We investigate the variability of the Nordic Seas freshwater content in the context of Fram Strait freshwater fluxes and North Atlantic Ocean dynamics. The freshwater content of the Nordic Seas is in turn thought to affect wintertime deep convection and air-sea heat fluxes, which influence cyclogenesis in the atmosphere. Here, we demonstrate that there is no apparent relationship between Nordic Seas hydrography and cyclogenesis, although cyclone activity in the Nordic Seas influences the strength of the Beaufort High and the Beaufort Gyre circulation.