Dynamics of the Arctic Pacific Water

Pacific Water (PW) enters the Arctic Ocean through Bering Strait, bringing heat, fresh water and nutrients from the northern Bering Sea. PW has a strong impact on ocean mixing, sea ice and ocean dynamics, as well as on heat and salt budgets and ocean biology. Pathways and the circulation of PW in the central Arctic Ocean are only partially understood due to the lack of observations. We simulate PW pathways by tracking it with a passive PW tracer released in Bering Strait during 1979-2010 in a suite of coupled sea ice-ocean models. Simulated PW water flows into the Arctic Ocean through the Barrow and Herald canyons and across the Herald Shoal and the central Chukchi shelf. One branch of PW follows the continental slope of Alaska into the Canadian Straits and enters the Baffin Bay. The other branch brings PW into the transpolar drift and then through Fram Strait into the Greenland Sea. The third branch transports PW into the Beaufort Gyre. We analyse changes in the PW pathways in the Arctic Ocean due to changes in the atmospheric wind, focusing on seasonal and inter-decadal variations in the PW pathways. We suggest a hypothesis relating variations in the PW pathways to the changes in the Ekman pumping and to the changes in vertical shear of the oceanic relative vorticity. We discuss the implications of the Pacific water variability for the recent changes in the Arctic heat and fresh water storage.