QuasiGeostrophic Diagnosis of Mixed-Layer Dynamics Embedded in a Mesoscale Turbulent Field

Type Article
Date 2016-01
Language English
Author(s) Chavanne Cedric P.1, Klein Patrice2
Affiliation(s) 1 : Univ Quebec, Inst Sci Mer Rimouski, 310 Allee Ursulines, Rimouski, PQ G5L 3A1, Canada.
2 : IFREMER CNRS UBO IRD, Lab Phys Oceans, Plouzane, France.
Source Journal Of Physical Oceanography (0022-3670) (Amer Meteorological Soc), 2016-01 , Vol. 46 , N. 1 , P. 275-287
DOI 10.1175/JPO-D-14-0178.1
WOS© Times Cited 8
Keyword(s) Circulation, Dynamics, Ageostrophic circulations, Mesoscale processes, Ocean dynamics, Vertical motion, Models and modeling, Diagnostics, Quasigeostrophic models
Abstract A quasigeostrophic model is developed to diagnose the three-dimensional circulation, including the vertical velocity, in the upper ocean from high-resolution observations of sea surface height and buoyancy. The formulation for the adiabatic component departs from the classical surface quasigeostrophic framework considered before since it takes into account the stratification within the surface mixed layer that is usually much weaker than that in the ocean interior. To achieve this, the model approximates the ocean with two constant stratification layers: a finite-thickness surface layer (or the mixed layer) and an infinitely deep interior layer. It is shown that the leading-order adiabatic circulation is entirely determined if both the surface streamfunction and buoyancy anomalies are considered. The surface layer further includes a diabatic dynamical contribution. Parameterization of diabatic vertical velocities is based on their restoring impacts of the thermal wind balance that is perturbed by turbulent vertical mixing of momentum and buoyancy. The model skill in reproducing the three-dimensional circulation in the upper ocean from surface data is checked against the output of a high-resolution primitive equation numerical simulation
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