Shelf-Basin Exchange in the Chukchi Sea
The observed ongoing decline of summer sea ice coverage in the Arctic Ocean results, in part, from heat carried by ocean waters. This heat enters the Arctic Ocean by direct solar heating and by the transport of heat with flows from the Atlantic Ocean and Bering Sea. The warm waters from the Atlantic Ocean are isolated from direct contact with the sea ice by subsurface colder waters. This project will develop a model that synthesizes our understanding of important physical processes in the Arctic Ocean, compare the model output to observations, use the model to increase understanding of the processes responsible for modulating heat flux to the sea ice, and understand the observed recent trends in those processes The principal investigator will study processes that lead to water mass transformation within the Chukchi Sea, exchange across the shelfbreak to the basin interior, and the melting of ice using a very high resolution regional numerical model in conjunction with recent and historical observations. The model is a realistically configured coupled ocean/sea ice model forced by synoptic atmospheric fields and flow through Bering Strait. Physical processes responsible for exchange of mass, heat, freshwater, and tracers across the shelfbreak will be diagnosed. The circulation and fluxes in the model will be compared with in-situ mooring and hydrographic data. The objectives of the planned study are to better understand the processes responsible for cross shelf exchange in the Pacific sector of the Arctic Ocean, their relation to ice melt in the interior, and how they might change in a changing Arctic climate. The focus of the regional model is to diagnose the mechanisms responsible for shelf-basin exchange and relate them to the basic forcing mechanisms in this region (flow through Bering Strait and the atmosphere). The efficiency of the regional model allows for large numbers of calculations to be carried out, and for hypotheses relating to exchange to be tested. Such a process-based approach allows for a general understanding of the controlling physics with broader implications for other regions and forcing scenarios. The principal investigator teaches graduate level classes in the MIT-WHOI Joint Program in Physical Oceanography, and the material developed during this project will be incorporated into his classes. He has also been involved in the GFD summer school and will offer summer school lectures about the understanding gained from this study. Undergraduate students strong in mathematics and physics will also be recruited to work on the model analysis through the WHOI Summer Student Fellowship program at no cost to this project. The PI also maintains a web site that summarizes and highlights his research interests for a broader audience.