Intensification of Near-Surface Currents and Shear in the Eastern Arctic Ocean

A 15-year (2004-2018) record of mooring observations from the upper 50 m ocean in the eastern Eurasian Basin reveals increased current speeds and shear, associated with an increasing coupling between wind, ice, and oceanic currents and their vertical shear over 2004-2018, particularly in summer. Substantial increases in both current speeds and shears in the upper 50 m are dominated by a two times amplification of currents in the semidiurnal band, which includes tides and wind-forced near-inertial oscillations. For the first time the strengthened upper ocean currents and shear are observed to coincide with weakening stratification. This coupling links the Atlantic Water heat to the sea ice, a consequence of which would be reducing regional sea ice volume. These results point to a new positive feedback mechanism in which reduced sea ice extent facilitates more energetic inertial oscillations and associated upper-ocean shear, thus leading in enhanced ventilation of the Atlantic water.