The fundamental goal of the Shelf-Basin Interactions (SBI) program is to understand the physical and biogeochemical processes that link the arctic shelves, slopes, and deep basins within the context of global change. These processes strongly influence the biology, chemistry, and physics of the Arctic Ocean and its associated ecosystems. The Arctic marine system is linked to the global ocean and atmosphere by both physical and biogeochemical mechanisms, such as the influence that freshwater outflows from the Arctic have on North Atlantic convection and thermohaline circulation of the world ocean. Arctic Ocean waters are strongly influenced by biogeochemical processes occurring over the arctic shelves and a synoptic understanding of these processes is essential for predicting, anticipating and ameliorating the impacts of climate change. For example, carbon dioxide fluxes from sources or sinks on Arctic shelves may have direct impacts on air temperatures and sea ice coverage, with negative ramifications for local marine resources and human populations that are dependent upon them for subsistence. The SBI program will specifically focus on identifying processes that are sentinel indicators of global change, including alteration of current biogeochemical cycles. These include:
- Physical modifications of North Pacific and other waters on the Chukchi shelf and slope, since these modifications subsequently affect both exchange across the continental slope and the thermohaline structure and circulation of the Arctic Ocean.
- Biogeochemical modifications of North Pacific and other waters over the Chukchi and Beaufort shelf and slope areas, with an emphasis on carbon, nutrients, and key organisms that represent a suite of trophic levels.
- Comparative studies over the wide Chukchi and narrow Beaufort shelves and adjacent slopes to facilitate extrapolation of the Western Arctic work to a Pan-Arctic perspective. Modeling of shelf-basin exchange processes and their sensitivity to global change will be an important methodology in this extrapolation.
- Quantify the major physical processes over the shelf and slope and their variability, including resolution of smaller scale (< 30 km) physical exchange processes along the shelf break and slope, since these appear critical to the disposition within the Arctic Ocean of mass, heat, salt, carbon and nutrients, from the shelves.
- Quantify the major biological and chemical processes over the shelf and slope and their variability, since the timing of biological rate processes relative to physical transport processes is critical to understanding ecosystem dynamics.
- Quantify the export of mass, heat, salt, carbon and nutrients into the Arctic Ocean and their variability.
Because of the markedly different summer and winter regimes in the Arctic, as well as the remarkable year-to-year variability, seasonal and interannual time series are required to identify the processes that control the functioning of the Arctic ecosystem. Therefore SBI will undertake time series studies to:
In summary, the goal of the SBI program is to provide a clear understanding of the physical and biogeochemical connections between the Arctic shelves, slopes, and deep basins that could be influenced by global change. The physical and chemical nature of seawater transiting the Western Arctic and entering the world ocean is defined by the physical and biogeochemical processes occurring over the large Western Arctic shelves. The current Arctic Ocean system and the cycling of carbon depends upon carbon export fluxes from the surrounding shelves. Changes in either the balance of shelf processes that modify the Pacific waters, or in the slope processes that control exchange with the deep basin, will likely result in major alterations of the Arctic marine environment. These alterations would also have significant societal consequences on local, regional, and national levels in areas as diverse as marine transporation, resource use, and climatic change. An understanding of these processes is therefore essential. This new understanding will in turn allow realistic assessment both of the potential responses of the Arctic system to global change, and of the role of these interactive processes on the global climate system.