Do Submesoscales Affect the Large-Scale Structure of the Upper Ocean?

Anirban Sinha aCalifornia Institute of Technology, Pasadena, California

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Jörn Callies aCalifornia Institute of Technology, Pasadena, California

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Dimitris Menemenlis bJet Propulsion Laboratory, Pasadena, California

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Abstract

Submesoscale baroclinic instabilities have been shown to restratify the surface mixed layer and to seasonally energize submesoscale turbulence in the upper ocean. But do these instabilities also affect the large-scale circulation and stratification of the upper thermocline? This question is addressed for the North Atlantic Subtropical Mode Water region with a series of numerical simulations at varying horizontal grid spacings (16, 8, 4, and 2 km). These simulations are realistically forced and integrated long enough for the thermocline to adjust to the presence or absence of submesoscales. Linear stability analysis indicates that a 2-km grid spacing is sufficient to resolve the most unstable mode of the wintertime mixed layer instability. As the resolution is increased, spectral slopes of horizontal kinetic energy flatten and vertical velocities increase in magnitude, consistent with previous regional and short-time simulations. The equilibrium stratification of the thermocline changes drastically as the grid spacing is refined from 16 to 8 km and mesoscale eddies are fully resolved. The thermocline stratification remains largely unchanged, however, between the 8-, 4-, and 2-km runs. This robustness is argued to arise from a mesoscale constraint on the buoyancy variance budget. Once mesoscale processes are resolved, the rate of mesoscale variance production is largely fixed. This constrains the variance destruction by submesoscale vertical buoyancy fluxes, which thus remain invariant across resolutions. The bulk impact of mixed layer instabilities on upper-ocean stratification in the Subtropical Mode Water region through an enhanced vertical buoyancy flux is therefore captured at 8-km grid spacing, even though the instabilities are severely underresolved.

Sinha’s current affiliation: Picarro Inc., Santa Clara, California.

© 2023 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

This article is included in the Climate Implications of Frontal Scale Air-Sea Interaction Special Collection.

This article is included in the Ocean Turbulence Special Collection.

Corresponding author: Anirban Sinha, as4479@columbia.edu

Abstract

Submesoscale baroclinic instabilities have been shown to restratify the surface mixed layer and to seasonally energize submesoscale turbulence in the upper ocean. But do these instabilities also affect the large-scale circulation and stratification of the upper thermocline? This question is addressed for the North Atlantic Subtropical Mode Water region with a series of numerical simulations at varying horizontal grid spacings (16, 8, 4, and 2 km). These simulations are realistically forced and integrated long enough for the thermocline to adjust to the presence or absence of submesoscales. Linear stability analysis indicates that a 2-km grid spacing is sufficient to resolve the most unstable mode of the wintertime mixed layer instability. As the resolution is increased, spectral slopes of horizontal kinetic energy flatten and vertical velocities increase in magnitude, consistent with previous regional and short-time simulations. The equilibrium stratification of the thermocline changes drastically as the grid spacing is refined from 16 to 8 km and mesoscale eddies are fully resolved. The thermocline stratification remains largely unchanged, however, between the 8-, 4-, and 2-km runs. This robustness is argued to arise from a mesoscale constraint on the buoyancy variance budget. Once mesoscale processes are resolved, the rate of mesoscale variance production is largely fixed. This constrains the variance destruction by submesoscale vertical buoyancy fluxes, which thus remain invariant across resolutions. The bulk impact of mixed layer instabilities on upper-ocean stratification in the Subtropical Mode Water region through an enhanced vertical buoyancy flux is therefore captured at 8-km grid spacing, even though the instabilities are severely underresolved.

Sinha’s current affiliation: Picarro Inc., Santa Clara, California.

© 2023 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

This article is included in the Climate Implications of Frontal Scale Air-Sea Interaction Special Collection.

This article is included in the Ocean Turbulence Special Collection.

Corresponding author: Anirban Sinha, as4479@columbia.edu

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  • Bachman, S. D., B. Fox-Kemper, J. R. Taylor, and L. N. Thomas, 2017: Parameterization of frontal symmetric instabilities. I: Theory for resolved fronts. Ocean Modell., 109, 7295, https://doi.org/10.1016/j.ocemod.2016.12.003.

    • Search Google Scholar
    • Export Citation
  • Balwada, D., K. S. Smith, and R. Abernathey, 2018: Submesoscale vertical velocities enhance tracer subduction in an idealized Antarctic circumpolar current. Geophys. Res. Lett., 45, 97909802, https://doi.org/10.1029/2018GL079244.

    • Search Google Scholar
    • Export Citation
  • Bates, N. R., A. C. Pequignet, R. J. Johnson, and N. Gruber, 2002: A short-term sink for atmospheric CO2 in subtropical mode water of the North Atlantic Ocean. Nature, 420, 489493, https://doi.org/10.1038/nature01253.

    • Search Google Scholar
    • Export Citation
  • Boccaletti, G., R. Ferrari, and B. Fox-Kemper, 2007: Mixed layer instabilities and restratification. J. Phys. Oceanogr., 37, 22282250, https://doi.org/10.1175/JPO3101.1.

    • Search Google Scholar
    • Export Citation
  • Bodner, A. S., B. Fox-Kemper, L. P. Van Roekel, J. C. McWilliams, and P. P. Sullivan, 2019: A perturbation approach to understanding the effects of turbulence on frontogenesis. J. Fluid Mech., 883, A25, https://doi.org/10.1017/jfm.2019.804.

    • Search Google Scholar
    • Export Citation
  • Brüggemann, N., and C. Eden, 2015: Routes to dissipation under different dynamical conditions. J. Phys. Oceanogr., 45, 21492168, https://doi.org/10.1175/JPO-D-14-0205.1.

    • Search Google Scholar
    • Export Citation
  • Buckingham, C. E., N. S. Lucas, S. E. Belcher, T. P. Rippeth, A. L. M. Grant, J. Le Sommer, A. O. Ajayi, and A. C. Naveira Garabato, 2019: The contribution of surface and submesoscale processes to turbulence in the open ocean surface boundary layer. J. Adv. Model. Earth Syst., 11, 40664094, https://doi.org/10.1029/2019MS001801.

    • Search Google Scholar
    • Export Citation
  • Burns, K. J., G. M. Vasil, J. S. Oishi, D. Lecoanet, and B. P. Brown, 2020: Dedalus: A flexible framework for numerical simulations with spectral methods. Phys. Rev. Res., 2, 023068, https://doi.org/10.1103/PhysRevResearch.2.023068.

    • Search Google Scholar
    • Export Citation
  • Callies, J., and R. Ferrari, 2018: Baroclinic instability in the presence of convection. J. Phys. Oceanogr., 48, 4560, https://doi.org/10.1175/JPO-D-17-0028.1.

    • Search Google Scholar
    • Export Citation
  • Callies, J., R. Ferrari, J. M. Klymak, and J. Gula, 2015: Seasonality in submesoscale turbulence. Nat. Commun., 6, 6862, https://doi.org/10.1038/ncomms7862.

    • Search Google Scholar
    • Export Citation
  • Callies, J., G. Flierl, R. Ferrari, and B. Fox-Kemper, 2016: The role of mixed-layer instabilities in submesoscale turbulence. J. Fluid Mech., 788, 541, https://doi.org/10.1017/jfm.2015.700.

    • Search Google Scholar
    • Export Citation
  • Callies, J., R. Barkan, and A. N. Garabato, 2020: Time scales of submesoscale flow inferred from a mooring array. J. Phys. Oceanogr., 50, 10651086, https://doi.org/10.1175/JPO-D-19-0254.1.

    • Search Google Scholar
    • Export Citation
  • Capet, X., J. C. McWilliams, M. J. Molemaker, and A. F. Shchepetkin, 2008: Mesoscale to submesoscale transition in the California Current system. Part I: Flow structure, eddy flux, and observational tests. J. Phys. Oceanogr., 38, 2943, https://doi.org/10.1175/2007JPO3671.1.

    • Search Google Scholar
    • Export Citation
  • Chassignet, E. P., and X. Xu, 2017: Impact of horizontal resolution (1/12° to 1/50°) on Gulf Stream separation, penetration, and variability. J. Phys. Oceanogr., 47, 19992021, https://doi.org/10.1175/JPO-D-17-0031.1.

    • Search Google Scholar
    • Export Citation
  • Daru, V., and C. Tenaud, 2004: High order one-step monotonicity-preserving schemes for unsteady compressible flow calculations. J. Comput. Phys., 193, 563594, https://doi.org/10.1016/j.jcp.2003.08.023.

    • Search Google Scholar
    • Export Citation
  • Dong, J., B. Fox-Kemper, H. Zhang, and C. Dong, 2020: The scale of submesoscale baroclinic instability globally. J. Phys. Oceanogr., 50, 26492667, https://doi.org/10.1175/JPO-D-20-0043.1.

    • Search Google Scholar
    • Export Citation
  • du Plessis, M., S. Swart, I. J. Ansorge, and A. Mahadevan, 2017: Submesoscale processes promote seasonal restratification in the Subantarctic Ocean. J. Geophys. Res. Oceans, 122, 29602975, https://doi.org/10.1002/2016JC012494.

    • Search Google Scholar
    • Export Citation
  • du Plessis, M., S. Swart, I. J. Ansorge, A. Mahadevan, and A. F. Thompson, 2019: Southern Ocean seasonal restratification delayed by submesoscale wind–front interactions. J. Phys. Oceanogr., 49, 10351053, https://doi.org/10.1175/JPO-D-18-0136.1.

    • Search Google Scholar
    • Export Citation
  • Eady, E. T., 1949: Long waves and cyclone waves. Tellus, 1, 3352, https://doi.org/10.3402/tellusa.v1i3.8507.

  • Forget, G., G. Maze, M. Buckley, and J. Marshall, 2011: Estimated seasonal cycle of North Atlantic eighteen degree water volume. J. Phys. Oceanogr., 41, 269286, https://doi.org/10.1175/2010JPO4257.1.

    • Search Google Scholar
    • Export Citation
  • Fox-Kemper, B., and D. Menemenlis, 2008: Can large eddy simulation techniques improve mesoscale rich ocean models? Ocean Modeling in an Eddying Regime, Geophys. Monogr., Vol. 177, Amer. Geophys. Union, 319–337, https://doi.org/10.1029/177GM19.

  • Fox-Kemper, B., R. Ferrari, and R. Hallberg, 2008: Parameterization of mixed layer eddies. Part I: Theory and diagnosis. J. Phys. Oceanogr., 38, 11451165, https://doi.org/10.1175/2007JPO3792.1.

    • Search Google Scholar
    • Export Citation
  • Fox-Kemper, B., and Coauthors, 2011: Parameterization of mixed layer eddies. III: Implementation and impact in global ocean climate simulations. Ocean Modell., 39, 6178, https://doi.org/10.1016/j.ocemod.2010.09.002.

    • Search Google Scholar
    • Export Citation
  • Fukumori, I., O. Wang, I. Fenty, G. Forget, P. Heimbach, and R. M. Ponte, 2020: Synopsis of the ECCO central production global ocean and sea-ice state estimate, version 4 release 4. Zenodo, accessed 1 February 2021, https://doi.org/10.5281/zenodo.3765929.

  • Garner, S. T., N. Nakamura, and I. M. Held, 1992: Nonlinear equilibration of two-dimensional Eady waves: A new perspective. J. Atmos. Sci., 49, 19841996, https://doi.org/10.1175/1520-0469(1992)049<1984:NEOTDE>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Garrett, C., and W. H. Munk, 1972: Space-time scales of internal waves. Geophys. Fluid Dyn., 3, 225264, https://doi.org/10.1080/03091927208236082.

    • Search Google Scholar
    • Export Citation
  • Gula, J., M. J. Molemaker, and J. C. McWilliams, 2014: Submesoscale cold filaments in the Gulf Stream. J. Phys. Oceanogr., 44, 26172643, https://doi.org/10.1175/JPO-D-14-0029.1.

    • Search Google Scholar
    • Export Citation
  • Gula, J., M. J. Molemaker, and J. C. McWilliams, 2016: Topographic generation of submesoscale centrifugal instability and energy dissipation. Nat. Commun., 7, 12811, https://doi.org/10.1038/ncomms12811.

    • Search Google Scholar
    • Export Citation
  • Hersbach, H., and Coauthors, 2020: The ERA5 global reanalysis. Quart. J. Roy. Meteor. Soc., 146, 19992049, https://doi.org/10.1002/qj.3803.

    • Search Google Scholar
    • Export Citation
  • Iudicone, D., K. B. Rodgers, Y. Plancherel, O. Aumont, T. Ito, R. M. Key, G. Madec, and M. Ishii, 2016: The formation of the ocean’s anthropogenic carbon reservoir. Sci. Rep., 6, 35473, https://doi.org/10.1038/srep35473.

    • Search Google Scholar
    • Export Citation
  • Jackett, D. R., and T. J. McDougall, 1995: Minimal adjustment of hydrographic profiles to achieve static stability. J. Atmos. Oceanic Technol., 12, 381389, https://doi.org/10.1175/1520-0426(1995)012<0381:MAOHPT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Karleskind, P., M. Levy, and L. Memery, 2011: Modifications of mode water properties by sub-mesoscales in a bio-physical model of the northeast Atlantic. Ocean Model., 39, 4760, https://doi.org/10.1016/j.ocemod. 2010.12.003.

    • Search Google Scholar
    • Export Citation
  • Kwon, Y.-O., and S. C. Riser, 2004: North Atlantic subtropical mode water: A history of ocean-atmosphere interaction 1961–2000. Geophys. Res. Lett., 31, L19307, https://doi.org/10.1029/2004GL021116.

    • Search Google Scholar
    • Export Citation
  • Large, W. G., and A. J. G. Nurser, 2001: Ocean surface water mass transformation. Ocean Circulation and Climate: Observing and Modeling the Global Ocean, G. Siedler, J. Church, and J. Gould, Eds., International Geophysics Series, Vol. 77, Academic Press, 317–336, http://nora.nerc.ac.uk/154885/.

  • Large, W. G., J. C. McWilliams, and S. C. Doney, 1994: Oceanic vertical mixing: A review and a model with a nonlocal boundary layer parameterization. Rev. Geophys., 32, 363403, https://doi.org/10.1029/94RG01872.

    • Search Google Scholar
    • Export Citation
  • Lévy, M., P. Klein, A.-M. Tréguier, D. Iovino, G. Madeca, S. Massona, and K. Takahashic, 2010: Modifications of gyre circulation by sub-mesoscale physics. Ocean Modell., 34, 115, https://doi.org/10.1016/j.ocemod.2010.04.001.

    • Search Google Scholar
    • Export Citation
  • Lévy, M., P. J. S. Franks, and K. S. Smith, 2018: The role of submesoscale currents in structuring marine ecosystems. Nat. Commun., 9, 4758, https://doi.org/10.1038/s41467-018-07059-3.

    • Search Google Scholar
    • Export Citation
  • Luyten, J. R., J. Pedlosky, and H. Stommel, 1983: The ventilated thermocline. J. Phys. Oceanogr., 13, 292309, https://doi.org/10.1175/1520-0485(1983)013%3C0292:TVT%3E2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Marshall, D., 1997: Subduction of water masses in an eddying ocean. J. Mar. Res., 55, 201222, https://doi.org/10.1357/0022240973224373.

    • Search Google Scholar
    • Export Citation
  • Marshall, J., A. Adcroft, C. Hill, L. Perelman, and C. Heisey, 1997: A finite-volume, incompressible Navier Stokes model for studies of the ocean on parallel computers. J. Geophys. Res., 102, 57535766, https://doi.org/10.1029/96JC02775.

    • Search Google Scholar
    • Export Citation
  • Marshall, J., H. Jones, R. Karsten, and R. Wardle, 2002: Can eddies set ocean stratification? J. Phys. Oceanogr., 32, 2638, https://doi.org/10.1175/1520-0485(2002)032<0026:CESOS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Mensa, J. A., Z. Garraffo, A. Griffa, T. M. Özgökmen, A. Haza, and M. Veneziani, 2013: Seasonality of the submesoscale dynamics in the Gulf Stream region. Ocean Dyn., 63, 923941, https://doi.org/10.1007/s10236-013-0633-1.

    • Search Google Scholar
    • Export Citation
  • Nakamura, N., and I. M. Held, 1989: Nonlinear equilibration of two-dimensional Eady waves. J. Atmos. Sci., 46, 30553064, https://doi.org/10.1175/1520-0469(1989)046<3055:NEOTDE>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Nguyen, A. T., H. Pillar, V. Ocaña, A. Bigdeli, T. A. Smith, and P. Heimbach, 2021: The Arctic Subpolar gyre sTate Estimate (ASTE): Description and assessment of a data-constrained, dynamically consistent ocean-sea ice estimate for 2002–2017. J. Adv. Model. Earth Syst., 13, e2020MS002398, https://doi.org/10.1029/2020MS002398.

    • Search Google Scholar
    • Export Citation
  • Palter, J. B., M. S. Lozier, and R. T. Barber, 2005: The effect of advection on the nutrient reservoir in the North Atlantic subtropical gyre. Nature, 437, 687692, https://doi.org/10.1038/nature03969.

    • Search Google Scholar
    • Export Citation
  • Renault, L., M. J. Molemaker, J. Gula, S. Masson, and J. C. McWilliams, 2016: Control and stabilization of the Gulf Stream by oceanic current interaction with the atmosphere. J. Phys. Oceanogr., 46, 34393453, https://doi.org/10.1175/JPO-D-16-0115.1.

    • Search Google Scholar
    • Export Citation
  • Sasaki, H., P. Klein, B. Qiu, and Y. Sasai, 2014: Impact of oceanic-scale interactions on the seasonal modulation of ocean dynamics by the atmosphere. Nat. Commun., 5, 5636, https://doi.org/10.1038/ncomms6636.

    • Search Google Scholar
    • Export Citation
  • Sasaki, H., P. Klein, Y. Sasai, and B. Qiu, 2017: Regionality and seasonality of submesoscale and mesoscale turbulence in the North Pacific Ocean. Ocean Dyn., 67, 11951216, https://doi.org/10.1007/s10236-017-1083-y.

    • Search Google Scholar
    • Export Citation
  • Schubert, R., J. Gula, R. J. Greatbatch, B. Baschek, and A. Biastoch, 2020: The submesoscale kinetic energy cascade: Mesoscale absorption of submesoscale mixed layer eddies and frontal downscale fluxes. J. Phys. Oceanogr., 50, 25732589, https://doi.org/10.1175/JPO-D-19-0311.1.

    • Search Google Scholar
    • Export Citation
  • Smith, K. M., P. E. Hamlington, and B. Fox-Kemper, 2016: Effects of submesoscale turbulence on ocean tracers. J. Geophys. Res. Oceans, 121, 908933, https://doi.org/10.1002/2015JC011089.

    • Search Google Scholar
    • Export Citation
  • Stammer, D., K. Ueyoshi, A. Köhl, W. G. Large, S. A. Josey, and C. I. Wunsch, 2004: Estimating air-sea fluxes of heat, freshwater, and momentum through global ocean data assimilation. J. Geophys. Res., 109, C05023, https://doi.org/10.1029/2003JC002082.

    • Search Google Scholar
    • Export Citation
  • Stone, P. H., 1966: On non-geostrophic baroclinic stability. J. Atmos. Sci., 23, 390400, https://doi.org/10.1175/1520-0469(1966)023<0390:ONGBS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Su, Z., J. Wang, P. Klein, A. F. Thompson, and D. Menemenlis, 2018: Ocean submesoscales as a key component of the global heat budget. Nat. Commun., 9, 775, https://doi.org/10.1038/s41467-018-02983-w.

    • Search Google Scholar
    • Export Citation
  • Taylor, J. R., and R. Ferrari, 2010: Buoyancy and wind-driven convection at mixed layer density fronts. J. Phys. Oceanogr., 40, 12221242, https://doi.org/10.1175/2010JPO4365.1.

    • Search Google Scholar
    • Export Citation
  • Taylor, J. R., S. Bachman, M. Stamper, P. Hosegood, K. Adams, J.-B. Sallee, and R. Torres, 2018: Submesoscale Rossby waves on the Antarctic circumpolar current. Sci. Adv., 4, eaao2824, https://doi.org/10.1126/sciadv.aao2824.

    • Search Google Scholar
    • Export Citation
  • Thomas, L. N., J. R. Taylor, R. Ferrari, and T. M. Joyce, 2013: Symmetric instability in the Gulf Stream. Deep-Sea Res. II, 91, 96110, https://doi.org/10.1016/j.dsr2.2013.02.025.

    • Search Google Scholar
    • Export Citation
  • Thompson, A. F., A. Lazar, C. Buckingham, A. C. Naveira Garabato, G. M. Damerell, and K. J. Heywood, 2016: Open-ocean submesoscale motions: A full seasonal cycle of mixed layer instabilities from gliders. J. Phys. Oceanogr., 46, 12851307, https://doi.org/10.1175/JPO-D-15-0170.1.

    • Search Google Scholar
    • Export Citation
  • Uchida, T., R. Abernathey, and S. Smith, 2017: Seasonality of eddy kinetic energy in an eddy permitting global climate model. Ocean Modell., 118, 4158, https://doi.org/10.1016/j.ocemod.2017.08.006.

    • Search Google Scholar
    • Export Citation
  • Wenegrat, J. O., L. N. Thomas, J. Gula, and J. C. McWilliams, 2018: Effects of the Submesoscale on the potential vorticity budget of ocean mode waters. J. Phys. Oceanogr., 48, 21412165, https://doi.org/10.1175/JPO-D-17-0219.1.

    • Search Google Scholar
    • Export Citation
  • Worthington, L. V., 1958: The 18° water in the Sargasso Sea. Deep-Sea Res., 5, 297305, https://doi.org/10.1016/0146-6313(58)90026-1.

    • Search Google Scholar
    • Export Citation
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