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Frontogenesis and frontal arrest of a dense filament in the oceanic surface boundary layer

Published online by Cambridge University Press:  21 December 2017

Peter P. Sullivan
Affiliation:
National Center for Atmospheric Research, Boulder, CO 80307, USA
James C. McWilliams
Affiliation:
Department of Atmospheric and Oceanic Sciences, UCLA, Los Angeles, CA 90095, USA
Corresponding
E-mail address:

Abstract

The evolution of upper ocean currents involves a set of complex, poorly understood interactions between submesoscale turbulence (e.g. density fronts and filaments and coherent vortices) and smaller-scale boundary-layer turbulence. Here we simulate the lifecycle of a cold (dense) filament undergoing frontogenesis in the presence of turbulence generated by surface stress and/or buoyancy loss. This phenomenon is examined in large-eddy simulations with resolved turbulent motions in large horizontal domains using ${\sim}10^{10}$ grid points. Steady winds are oriented in directions perpendicular or parallel to the filament axis. Due to turbulent vertical momentum mixing, cold filaments generate a potent two-celled secondary circulation in the cross-filament plane that is frontogenetic, sharpens the cross-filament buoyancy and horizontal velocity gradients and blocks Ekman buoyancy flux across the cold filament core towards the warm filament edge. Within less than a day, the frontogenesis is arrested at a small width, ${\approx}100~\text{m}$ , primarily by an enhancement of the turbulence through a small submesoscale, horizontal shear instability of the sharpened filament, followed by a subsequent slow decay of the filament by further turbulent mixing. The boundary-layer turbulence is inhomogeneous and non-stationary in relation to the evolving submesoscale currents and density stratification. The occurrence of frontogenesis and arrest are qualitatively similar with varying stress direction or with convective cooling, but the detailed evolution and flow structure differ among the cases. Thus submesoscale filament frontogenesis caused by boundary-layer turbulence, frontal arrest by frontal instability and frontal decay by forward energy cascade, and turbulent mixing are generic processes in the upper ocean.

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JFM Papers
Copyright
© 2017 Cambridge University Press 

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References

Adrian, R. J. 2007 Hairpin vortex organization in wall turbulence. Phys. Fluids 19, 041301.CrossRefGoogle Scholar
Boccaletti, G., Ferrari, R. & Fox-Kemper, B. 2007 Mixed layer instabilities and restratification. J. Phys. Oceanogr. 37, 22282250.CrossRefGoogle Scholar
Capet, X., McWilliams, J. C., Molemaker, M. J. & Shchepetkin, A. 2008 Mesoscale to submesoscale transition in the California current cystem. II: frontal processes. J. Phys. Oceanogr. 38, 4464.CrossRefGoogle Scholar
Cornejo, P. & Sepúlveda, H. H. 2016 Computational fluid dynamics modelling of a midlatitude small scale upper ocean front. J. Appl. Fluid Mech. 9, 18511863.Google Scholar
Deardorff, J. W. 1972a Numerical investigation of neutral and unstable planetary boundary layers. J. Atmos. Sci. 29, 91115.2.0.CO;2>CrossRefGoogle Scholar
Deardorff, J. W. 1972b Three-dimensional numerical modeling of the planetary boundary layer. In Workshop on Micrometeorology (ed. Haugen, D. A.), pp. 271311. American Meteorological Society.Google Scholar
Fox-Kemper, B., Ferrari, R. & Hallberg, R. W. 2008 Parameterization of mixed layer eddies. Part 1. Theory and diagnosis. J. Phys. Oceanogr. 38, 11451165.CrossRefGoogle Scholar
Gill, A. E. 1982 Atmosphere-Ocean Dynamics. Academic Press.Google Scholar
Gula, J., Molemaker, M. J. & McWilliams, J. C. 2014 Submesoscale cold filaments in the Gulf Stream. J. Phys. Oceanogr. 44, 26172643.CrossRefGoogle Scholar
Hamlington, P. E., Van Roekel, L. P., Fox-Kemper, B., Julien, K. & Chini, G. P. 2014 Langmuir-Submesoscale interactions: descriptive analysis of multiscale frontal spindown simulations. J. Phys. Oceanogr. 44, 22492272.CrossRefGoogle Scholar
Hoskins, B. J. 1982 The mathematical theory of frontogenesis. Annu. Rev. Fluid Mech. 14, 131151.CrossRefGoogle Scholar
Hoskins, B. J. & Bretherton, F. P. 1972 Atmospheric frontogenesis models: mathematical formulation and solution. J. Atmos. Sci. 29, 1137.2.0.CO;2>CrossRefGoogle Scholar
Hussain, A. K. M. F. & Reynolds, W. C. 1970 The mechanics of an organized wave in turbulent shear flow. J. Fluid Mech. 41, 241258.CrossRefGoogle Scholar
Hutchins, N. & Marusic, I. 2007 Evidence of very long meandering features in the logarithmic region of turbulent boundary layers. J. Fluid Mech. 579, 128.CrossRefGoogle Scholar
Large, W. G., McWilliams, J. C. & Doney, S. C. 1994 Oceanic vertical mixing: a review and a model with a nonlocal boundary layer parameterization. Rev. Geophys. 32, 363403.CrossRefGoogle Scholar
Large, W. G. & Pond, S. 1981 Open ocean flux measurements in moderate to strong winds. J. Phys. Oceanogr. 11, 324336.2.0.CO;2>CrossRefGoogle Scholar
Mahadevan, A. & Tandon, A. 2006 An analysis of mechanisms for submesoscale vertical motion at ocean fronts. Ocean Model 14, 241256.CrossRefGoogle Scholar
McWilliams, J. C. 2016 Submesoscale currents in the ocean. Proc. R. Soc. Lond. A 472, 132.CrossRefGoogle ScholarPubMed
McWilliams, J. C. 2017 Submesoscale surface fronts and filaments: secondary circulation, buoyancy flux, and frontogenesis. J. Fluid Mech. 823, 391432.CrossRefGoogle Scholar
McWilliams, J. C., Colas, F. & Molemaker, M. J. 2009a Cold filamentary intensification and oceanic surface convergence lines. Geophys. Res. Lett. 36, 15, L18602.CrossRefGoogle Scholar
McWilliams, J. C., Gula, J., Molemaker, M. J., Renault, L. & Shchepetkin, A. F. 2015 Filament frontogenesis by boundary layer turbulence. J. Phys. Oceanogr. 45, 19882005.CrossRefGoogle Scholar
McWilliams, J. C., Moeng, C.-H. & Sullivan, P. P. 1999 Turbulent fluxes and coherent structures in marine boundary layers: investigations by large-eddy simulation. In Air-Sea Exchange: Physics, Chemistry, Dynamics, and Statistics (ed. Geernaert, G.), pp. 507538. Kluwer.CrossRefGoogle Scholar
McWilliams, J. C., Molemaker, M. J. & Olafsdottir, E. I. 2009b Linear fluctuation growth during frontogenesis. J. Phys. Oceanogr. 39, 31113129.CrossRefGoogle Scholar
McWilliams, J. C., Sullivan, P. P. & Moeng, C.-H. 1997 Langmuir turbulence in the ocean. J. Fluid Mech. 334, 130.CrossRefGoogle Scholar
Moeng, C.-H. 1984 A large-eddy simulation model for the study of planetary boundary-layer turbulence. J. Atmos. Sci. 41, 20522062.2.0.CO;2>CrossRefGoogle Scholar
Moeng, C.-H. & Sullivan, P. P. 1994 A comparison of shear and buoyancy driven planetary-boundary-layer flows. J. Atmos. Sci. 51, 9991022.2.0.CO;2>CrossRefGoogle Scholar
Moeng, C.-H. & Sullivan, P. P. 2015 Large-eddy simulation. In Encyclopedia of Atmospheric Sciences, 2nd edn. (ed. North, G. R., Zhang, F. & Pyle, J.), vol. 4, pp. 232240. Academic Press.CrossRefGoogle Scholar
Moeng, C. H. & Wyngaard, J. C. 1988 Spectral analysis of large-eddy simulations of the convective boundary layer. J. Atmos. Sci. 45, 35733587.2.0.CO;2>CrossRefGoogle Scholar
Özgökmen, T. M., Poje, A. C., Fischer, P. F. & Haza, A. C. 2011 Large eddy simulations of mixed layer instabilities and sampling strategies. Ocean Model. 39, 311331.CrossRefGoogle Scholar
Samelson, R. M. & Skyllingstad, E. D. 2016 Frontogenesis and turbulence: a numerical simulation. J. Atmos. Sci. 73, 50255040.CrossRefGoogle Scholar
Schmidt, H. & Schumann, U. 1989 Coherent structure of the convective boundary layer. J. Fluid Mech. 200, 511562.CrossRefGoogle Scholar
Shchepetkin, A. F. & McWilliams, J. C. 2005 The Regional Oceanic Modeling System (ROMS): a split-explicit, free-surface, topography-following-coordinate ocean model. Ocean Model. 9, 347404.CrossRefGoogle Scholar
Skyllingstad, E. D. & Samelson, R. M. 2012 Baroclinic frontal instabilities and turbulent mixing in the surface boundary layer. Part I: unforced simulations. J. Phys. Oceanogr. 42, 17011716.CrossRefGoogle Scholar
Sullivan, P. P. & McWilliams, J. C. 2010 Dynamics of winds and currents coupled to surface waves. Annu. Rev. Fluid Mech. 42, 1942.CrossRefGoogle Scholar
Sullivan, P. P. & McWilliams, J. C. 2017 Frontal turbulence in the upper ocean boundary layer. J. Fluid Mech. (to be submitted).Google Scholar
Sullivan, P. P., McWilliams, J. C. & Melville, W. K. 2004 The oceanic boundary layer driven by wave breaking with stochastic variability. Part 1. Direct numerical simulations. J. Fluid Mech. 507, 143174.CrossRefGoogle Scholar
Sullivan, P. P., McWilliams, J. C. & Melville, W. K. 2007 Surface gravity wave effects in the oceanic boundary layer: large-eddy simulation with vortex force and stochastic breakers. J. Fluid Mech. 593, 405452.CrossRefGoogle Scholar
Sullivan, P. P., McWilliams, J. C. & Moeng, C.-H. 1994 A subgrid-scale model for large-eddy simulation of planetary boundary-layer flows. Boundary-Layer Meteorol. 71, 247276.CrossRefGoogle Scholar
Sullivan, P. P., McWilliams, J. C. & Moeng, C.-H. 1996 A grid nesting method for large-eddy simulation of planetary boundary layer flows. Boundary-Layer Meteorol. 80, 167202.CrossRefGoogle Scholar
Sullivan, P. P. & Patton, E. G. 2011 The effect of mesh resolution on convective boundary-layer statistics and structures generated by large-eddy simulation. J. Atmos. Sci. 68, 23952415.CrossRefGoogle Scholar
Sullivan, P. P., Romero, L., McWilliams, J. C. & Melville, W. K. 2012 Transient evolution of Langmuir turbulence in ocean boundary layers driven by hurricane winds and waves. J. Phys. Oceanogr. 42, 19591980.CrossRefGoogle Scholar
Suzuki, N., Fox-Kemper, B., Hamlington, P. E. & Roekel, L. P. V. 2016 Surface waves affect frontogenesis. J. Geophys. Res. Oceans 121, 35973624.CrossRefGoogle Scholar
Taylor, J. R. & Ferrari, R. 2009 On the equlibration of a symmetrically unstable front via a secondary shear instability. J. Fluid Mech. 622, 103113.CrossRefGoogle Scholar
Tennekes, H. & Lumley, J. L. 1972 A First Course In Turbulence. MIT Press.Google Scholar
Thomas, L. N. 2005 Destruction of potential vorticity by winds. J. Phys. Oceanogr. 35, 24572466.CrossRefGoogle Scholar
Thomas, L. N., Ferrari, R. & Joyce, T. M. 2013 Symmetric instability in the gulf stream. Deep-Sea Res. II 91, 96110.CrossRefGoogle Scholar
Thomas, L. N. & Lee, C. 2005 Intensification of ocean fronts by down-front winds. J. Phys. Oceanogr. 35, 10861102.CrossRefGoogle Scholar

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