Upper-layer circulation at the mouth of Amundsen Gulf, Arctic Ocean

Abstract

Amundsen Gulf, located between the Canadian north slope and Banks Island, is the western-most entrance to the Canadian Arctic Archipelago, providing a bridge between the western Arctic Ocean and the North Atlantic. Using timeseries from 13 moorings in the vicinity of the mouth of Amundsen Gulf deployed from 2003 to 2004, we investigate the mean state and dominant variability of the circulation in the upper 50 m layer which consists of boundary currents on both sides of the gulf and anticyclonic recirculation in the interior. We find that the flow on the western side of the gulf switches directions in response to the wind: inflow under northwesterly winds and outflow under southeasterly winds. Such a relationship persists throughout the year, except during periods of fast ice coverage. By contrast, the current on the eastern side of Amundsen Gulf consistently flows into the gulf for most of the year and is only weakly correlated with the western boundary current or local winds. Instead, the flow aligns more with the circulation along the eastern side of Banks Island which is linked to the southeastern extension and movement of the Beaufort Gyre, and, in turn, the basin-scale wind stress curl. Three distinct water masses were observed at the mouth of the gulf during the year-long period: fresh water in fall that originates in the basin and penetrates into the gulf; cold/salty water in winter that is intermittently advected into the gulf from the eastern boundary current; and warm water in summer that appears in open ocean regions where atmospheric heating occurs, independent of the detailed circulation structure.