The interaction of recirculation gyres and a deep boundary current

TitleThe interaction of recirculation gyres and a deep boundary current
Publication TypeJournal Article
Year of Publication2018
AuthorsLe Bras I.A, Jayne SR, Toole J.M
JournalJournal of Physical Oceanography
Volume48
Pagination573-590
Date Published2018/03
Type of ArticleArticle
ISBN Number0022-3670
Accession NumberWOS:000430757700006
Keywordsbottom friction; circulation; grand-banks; gulf-stream; inertial recirculation; labrador sea-water; low-frequency variability; oceanography; Potential vorticity; radiation; subpolar north-atlantic; wave
Abstract

Motivated by the proximity of the Northern Recirculation Gyre and the deep western boundary current in the North Atlantic, an idealized model is used to investigate how recirculation gyres and a deep flow along a topographic slope interact. In this two-layer quasigeostrophic model, an unstable jet imposed in the upper layer generates barotropic recirculation gyres. These are maintained by an eddy-mean balance of potential vorticity (PV) in steady state. The authors show that the topographic slope can constrain the northern recirculation gyre meridionally and that the gyre's adjustment to the slope leads to increased eddy PV fluxes at the base of the slope. When a deep current is present along the topographic slope in the lower layer, these eddy PV fluxes stir the deep current and recirculation gyre waters. Increased proximity to the slope dampens the eddy growth rate within the unstable jet, altering the geometry of recirculation gyre forcing and leading to a decrease in overall eddy PV fluxes. These mechanisms may shape the circulation in the western North Atlantic, with potential feedbacks on the climate system.

DOI10.1175/jpo-d-17-0206.1
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