SGER - Radium Tracer Sampling of Eddies off the Beaufort Shelf

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The shelf areas of the Arctic Ocean comprise some 25% of the world's total, even though that sea contains only 2% of the ocean's waters. The influence of the shelf, then, is anomalously high in the Arctic.It is known that the influence of the shelf on the composition of ocean waters can be quantified through measurements of various ratios of radium isotopes. Both Ra228 (T = 5.77 yr) and Ra224 (T = 3.64 da) are elevated in shelf waters as compared to oceanic waters, and the ratio of these species to Ra226 (T = 1620 yr) yields measures of the relative influence of the shelf.This SGER proposes to have radium measurements incorporated into the 2004 Shelf-Basin Interaction Program cruise of Sep-Oct (R. Pickart, Chief Scientist). The work will entail two parts:(1) measurements taken in the core of the boundary current (along the Beaufort Sea shelf) will reveal the age and makeup of the boundary current water, and (2) radium isotope measurements taken during physical oceanographic surveys of small eddies in the region will reveal the source of the eddy water, and possibly its fate. This work will enhance the autonomous data collection by in situ moorings, provide new information on eddy formation off the Beaufort shelf, and lead to eventual incorporation of radium measurements in autonomous data collection efforts such as the proposed North Slope observatory.