Edge of the Arctic Shelf
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Polar projection map of the Arctic Ocean and expedition
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The Expedition - Overview
Overview | Objectives | Science Crew | The Ship

This cruise is our third year of oceanographic field work as part of the Western Arctic Shelf Basin Interactions (SBI) Experiment. To read dispatches from previous cruises, check the 2002 Dispatches and the 2003 Dispatches.

SBI is a multi-year, multi-disciplinary program sponsored jointly by the National Science Foundation’s Office of Polar Programs and the High-latitude branch of the Office of Naval Research. The overall goal is to understand how the Arctic shelves communicate with the interior basin from a coupled physical--biogeochemical standpoint. The premise is that this system is in a delicate balance that could be upset by global change, which in turn could have important ramifications. These include possible melting of portions of the polar ice cover, changes in export of water to the global ocean, and alteration of the food web with significant consequences for native populations. From the physical oceanographic perspective the goal is straightforward: understand how shelf water is transferred, at the continental shelfbreak, to the interior basin in order to help maintain the “cold halocline” of the Arctic Ocean. This is the salty layer at mid-depth which shields the surface ice cover from the warm deep water. If this shield is weakened, there is more than enough heat contained in the underlying Atlantic-origin water to start melting the ice from below.

SBI is divided into three phases:

Phase 1 (1999-2002) - Retrospective data analysis and modeling to help define a new measurement program.

Phase 2 (2002-2004) - Data collection in the Chukchi and Beaufort Seas, with continued regional modeling.

Phase 3 (2004) - Data/model synthesis to develop realistic descriptions and predictions of Arctic climate change.

Specific questions that SBI will focus on include:

  1. How is the inflowing water from Bering Strait transformed as it flows across the Chukchi shelf? How is this water subsequently transferred into the interior Arctic upon reaching the shelf edge?

  2. What are the major biological and chemical processes linking the outer shelf to the deep basin, and to what extent are they governed by the physical exchange processes?

  3. How do exchange mechanisms differ between the wide Chukchi and narrow Beaufort shelves and adjacent slopes?

  4. What are the variations in this system from season to season and year to year?
Answering these questions will help create a more general picture of Arctic shelf-basin exchange.