Western Arctic shelfbreak eddies : formation and transport
Spall, Michael A.
Pickart, Robert S.
Fratantoni, Paula S.
Plueddemann, Albert J.
MetadataShow full item record
The mean structure and time-dependent behavior of the shelfbreak jet along the southern Beaufort Sea, and its ability to transport properties into the basin interior via eddies are explored using high-resolution mooring data and an idealized numerical model. The analysis focuses on springtime, when weakly stratified winter-transformed Pacific water is being advected out of the Chukchi Sea. When winds are weak, the observed jet is bottom trapped with a low potential vorticity core and has maximum mean velocities of O(25 cm s−1) and an eastward transport of 0.42 Sv (1 Sv ≡ 106 m3 s−1). Despite the absence of winds, the current is highly time dependent, with relative vorticity and twisting vorticity often important components of the Ertel potential vorticity. An idealized primitive equation model forced by dense, weakly stratified waters flowing off a shelf produces a mean middepth boundary current similar in structure to that observed at the mooring site. The model boundary current is also highly variable, and produces numerous strong, small anticyclonic eddies that transport the shelf water into the basin interior. Analysis of the energy conversion terms in both the mooring data and the numerical model indicates that the eddies are formed via baroclinic instability of the boundary current. The structure of the eddies in the basin interior compares well with observations from drifting ice platforms. The results suggest that eddies shed from the shelfbreak jet contribute significantly to the offshore flux of heat, salt, and other properties, and are likely important for the ventilation of the halocline in the western Arctic Ocean. Interaction with an anticyclonic basin-scale circulation, meant to represent the Beaufort gyre, enhances the offshore transport of shelf water and results in a loss of mass transport from the shelfbreak jet.
Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 1644-1668, doi:10.1175/2007JPO3829.1.
Showing items related by title, author, creator and subject.
Nikolopoulos, Anna; Pickart, Robert S.; Fratantoni, Paula S.; Shimada, Koji; Torres, Daniel J.; Jones, E. Peter (2008-01-16)From August 2002 to September 2004 a high-resolution mooring array was maintained across the western Arctic boundary current in the Beaufort Sea north of Alaska. The array consisted of profiling instrumentation, providing ...
Yano, Yuriko; Shaver, Gaius R.; Giblin, Anne E.; Rastetter, Edward B.; Nadelhoffer, Knute J. (2009-06-12)We examined short- and long-term nitrogen (N) dynamics and availability along an arctic hillslope in Alaska, USA, using stable isotope of nitrogen (15N), as a tracer. Tracer levels of 15NH4+ were sprayed once onto the ...
Cole, Sylvia T.; Timmermans, Mary-Louise; Toole, John M.; Krishfield, Richard A.; Thwaites, Fredrik T. (American Meteorological Society, 2014-05)The ice–ocean system is investigated on inertial to monthly time scales using winter 2009–10 observations from the first ice-tethered profiler (ITP) equipped with a velocity sensor (ITP-V). Fluctuations in surface winds, ...