Transport through Unimak Pass, Alaska

We examined inflow through Unimak Pass (<200 m deep), which is the only major connection between the shelves of the North Pacific Ocean and the eastern Bering Sea. Geostrophic transport was generally northward from the Gulf of Alaska into the Bering Sea. The flow through the pass appeared to be modulated by the seasonal cycle of freshwater discharge. On shorter time scales, transport also was affected by semi-daily variations in tidal mixing. This effect was significant and not anticipated. Near-bottom currents, measured from moorings, were maximum during winter, and significantly correlated (r=0.7) with the alongshore winds. Although the flow through Unimak Pass transported some nutrients from the North Pacific Ocean, the Gulf of Alaska shelf is not the major source of nutrients to the Bering Sea shelf.