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Oceanic wave-balanced surface fronts and filaments

Published online by Cambridge University Press:  01 August 2013

James C. McWilliams  and
Baylor Fox-Kemper
James C. McWilliams*
Affiliation:
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095-1565, USA
Baylor Fox-Kemper
Affiliation:
Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO 80309-0311, USA
*
†Email address for correspondence: jcm@atmos.ucla.edu
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Abstract

A geostrophic, hydrostatic, frontal or filamentary flow adjusts conservatively to accommodate a surface gravity wave field with wave-averaged, Stokes-drift vortex and Coriolis forces in an altered balanced state. In this altered state, the wave-balanced perturbations have an opposite cross-front symmetry to the original geostrophic state; e.g. the along-front flow perturbation is odd-symmetric about the frontal centre while the geostrophic flow is even-symmetric. The adjustment tends to make the flow scale closer to the deformation radius, and it induces a cross-front shape displacement in the opposite direction to the overturning effects of wave-aligned down-front and up-front winds. The ageostrophic, non-hydrostatic, adjusted flow may differ from the initial flow substantially, with velocity and buoyancy perturbations that extend over a larger and deeper region than the initial front and Stokes drift. The largest effect occurs for fronts that are wider than the mixed layer deformation radius and that fill about two-thirds of a well-mixed surface layer, with the Stokes drift spanning only the shallowest part of the mixed layer. For even deeper mixed layers, and especially for thinner or absent mixed layers, the wave-balanced adjustments are not as large.

JFM classification

Geophysical and Geological Flows: Ocean processes Waves/Free-surface Flows: Surface gravity waves Geophysical and Geological Flows: Waves in rotating fluids
Type
Papers
Information
Journal of Fluid Mechanics , Volume 730 , 10 September 2013 , pp. 464 - 490
Copyright
©2013 Cambridge University Press 

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References

Boyd, J. P. 2000 Chebyshev and Fourier Spectral Methods. Dover.Google Scholar
de Boyer Montégut, C., Fischer, G., Lazar, A. S. & Iudicone, D. 2004 Mixed layer depth over the global ocean: an examination of profile data and a profile-based climatology. J. Geophys. Res. 109, C12003.Google Scholar
Cavaleri, L., Fox-Kemper, B. & Hemer, M. 2012 Wind waves in the coupled climate system. J. Geophys. Res. Bull. Am. Meteorol. Soc. 93, 1651–1661.CrossRefGoogle Scholar
Craik, A. D. D. & Leibovich, S. 1976 A rational model for Langmuir circulation. J. Fluid Mech. 73, 401–426.CrossRefGoogle Scholar
D’Asaro, E. A. 2001 Turbulent vertical kinetic energy in the ocean mixed layer. J. Phys. Oceanogr. 31, 3530–3537.2.0.CO;2>CrossRefGoogle Scholar
Fox-Kemper, B., Ferrari, R. & Hallberg, R. W. 2008 Parameterization of mixed layer eddies. Part 1. Theory and diagnosis. J. Phys. Oceanogr. 38, 1145–1165.Google Scholar
Gent, P. R. & McWilliams, J. C. 1983 Consistent balanced models in bounded and periodic domains. Dyn. Atmos. Oceans 7, 67–93.CrossRefGoogle Scholar
Gjaja, I. & Holm, D. D. 1996 Self-consistent Hamiltonian dynamics of wave mean-flow interaction for a rotating stratified incompressible fluid. Physica D 98, 343–378.Google Scholar
Guenther, R. & Lee, J. W. 1996 Partial Differential Equations of Mathematical Physics and Integral Equations. Dover.Google Scholar
Hamlington, P. E., Roekel, L. P. Van, Fox-Kemper, B. & Julien, K. 2013 Langmuir–submesoscale interactions: descriptive analysis of multiscale simulations. J. Phys. Oceanogr. (submitted).Google Scholar
Leibovich, S. 1983 The form and dynamics of Langmuir circulations. Annu. Rev. Fluid Mech. 15, 391–427.Google Scholar
Li, K., Zhang, Z., Chini, G. & Flierl, G. 2012 Langmuir circulation: an agent for vertical restratification? J. Phys. Oceanogr. 42, 1945–1958.Google Scholar
Lin, S. J. & Pierrehumbert, R. T. 1988 Does Ekman friction suppress baroclinic instability? J. Atmos. Sci. 45, 2920–2933.Google Scholar
McWilliams, J. C. 2006 Fundamentals of Geophysical Fluid Dynamics. Cambridge University Press.Google Scholar
McWilliams, J. C., Molemaker, M. J. & Olafsdottir, E. I. 2009 Linear fluctuation growth during frontogenesis. J. Phys. Oceanogr. 39, 3111–3129.Google Scholar
McWilliams, J. C., Restrepo, J. M. & Lane, E. M. 2004 An asymptotic theory for the interaction of waves and currents in coastal waters. J. Fluid Mech. 511, 135–178.Google Scholar
McWilliams, J. C., Sullivan, P. P. & Moeng, C. H. 1997 Langmuir turbulence in the ocean. J. Fluid Mech. 334, 1–30.CrossRefGoogle Scholar
Polton, J. A. & Belcher, S. E. 2007 Langmuir turbulence and deeply penetrating jets in an unstratified mixed layer. J. Geophys. Res. 112, C09020.Google Scholar
Thomas, L. N. 2005 Destruction of potential vorticity by winds. J. Phys. Oceanogr. 35, 2457–2466.Google Scholar
Uchiyama, Y., McWilliams, J. C. & Shchepetkin, A. F. 2010 Wave–current interaction in an oceanic circulation model with a vortex-force formalism: application to the surf zone. Ocean Model. 34, 16–35.CrossRefGoogle Scholar
Webb, A. & Fox-Kemper, B. 2011 Wave spectral moments and Stokes drift estimation. Ocean Model. 40, 273–288.Google Scholar