Microstructure observations of turbulent heat fluxes in a warm-core Canada Basin eddy

TitleMicrostructure observations of turbulent heat fluxes in a warm-core Canada Basin eddy
Publication TypeJournal Article
Year of Publication2018
AuthorsFine E.C, MacKinnon JA, Alford MH, Mickett J.B
JournalJournal of Physical Oceanography
Volume48
Pagination2397-2418
Date Published2018/10
Type of ArticleArticle
ISBN Number0022-3670
Accession NumberWOS:000446819000002
KeywordsAnticyclones; Arctic; arctic-ocean; Beaufort Sea; Diapycnal mixing; double-diffusive intrusions; eddies; inertial; internal waves; kinetic-energy dissipation; mediterranean salt lens; Mixing; observations; oceanography; pacific water; sea-ice; Ship; thermohaline steps; wave-propagation
Abstract

An intrahalocline eddy was observed on the Chukchi slope in September of 2015 using both towed CTD and microstructure temperature and shear sections. The core of the eddy was 6 degrees C, significantly warmer than the surrounding -1 degrees C water and far exceeding typical temperatures of warm-core Arctic eddies. Microstructure sections indicated that outside of the eddy the rate of dissipation of turbulent kinetic energy epsilon was quite low . Three different processes were associated with elevated epsilon. Double-diffusive steps were found at the eddy's top edge and were associated with an upward heat flux of 5 W m(-2). At the bottom edge of the eddy, shear-driven mixing played a modest role, generating a heat flux of approximately 0.5 W m(-2) downward. Along the sides of the eddy, density-compensated thermohaline intrusions transported heat laterally out of the eddy, with a horizontal heat flux of 2000 W m(-2). Integrating these fluxes over an idealized approximation of the eddy's shape, we estimate that the net heat transport due to thermohaline intrusions along the eddy flanks was 2 GW, while the double-diffusive flux above the eddy was 0.4 GW. Shear-driven mixing at the bottom of the eddy accounted for only 0.04 GW. If these processes continued indefinitely at the same rate, the estimated life-span would be 1-2 years. Such eddies may be an important mechanism for the transport of Pacific-origin heat, freshwater, and nutrients into the Canada Basin.

DOI10.1175/jpo-d-18-0028.1
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