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The Transport Pathways of the Dense Water Formed in the Western Arctic Polynyas and Their Transfonnation under Predicted Future Regional Climate

Weifeng Zhang, Applied Ocean Physics & Engineering

Arctic Research Initiative
2011 Funded Project

Abstract

Coastal polynyas are important for the Arctic climate because they supply a substantial portion of the Arctic cold halocline water, which separates the surface sea ice, a major component of the Arctic climate, from the deep warm water and prevents the melt of ice cover by the heat stored in the deep ocean. Polynyas formed along the coast ofthe Wrangel Island and the Arctic coast of Alaska (between Cape Lisburne and Point Barrow) can potentially provide a significant amount of dense water to the Arctic cold halocline, owing to their closeness, respectively, to the Herald and Barrow Canyons that connect directly to the shelf edge and transports Pacific water into the Arctic basins. Surveys of the Herald and Barrow Canyons showed that cold water possibly formed in the neighboring polynyas enter the canyons and, together with Pacific water, flow down-canyon onto the shelf edge. Despite many years of study in these regions, several key scientific questions remain unanswered: (I) What are the transport pathways of the dense water formed in the Wrangel Island and Alaskan coastal polynyas? (2) What drives the transport of the dense water? (3) How will the dense water transport pathways be different under predicted future regional climate?

To answer these questions, I propose to use a high-resolution state-of-the-art numerical model to investigate the transport of the dense water formed in the Wrangel Island and Alaska coastal polynyas. The model will have both ocean and sea ice components and will take into consideration the influences oflarge scale atmospheric, oceanic and sea ice activities. After being validated against satellite measurement of sea ice concentration and survey observations of the water conditions, the model will be used to (i) quantify the volume of the dense water formed in the Wrangel Island and Alaska coastal polynyas, (ii) examine the transport pathways of the dense water, (iii) diagnose the influences of various forcing factors (along-shelf current, winds, tides, ice cover, Bering Strait inflow) on the transport pathways, and (iv) investigate the transformation of the transport pathways under predicted future regional climate.

The proposed research aligns with the Arctic Research Initiative of WHO I. Results of this project will contribute to the overall understanding of the circulation in the western Arctic; shed light on how dense water formed in coastal polynyas in general is transported to the Arctic basins; and pave the way for model-observation integrated studies of the biophysical interaction in the area. They will also be used to support a research proposal to the National Science Foundation in the near future.

Last updated: July 8, 2011