Equilibration and Lateral Spreading of a Strip-Shaped Convective Region

S. D. Danilov A. M. Obukhov Institute for Atmospheric Physics, Russian Academy of Sciences, Moscow, Russia

Search for other papers by S. D. Danilov in
Current site
Google Scholar
PubMed
Close
,
V. M. Gryanik A. M. Obukhov Institute for Atmospheric Physics, Russian Academy of Sciences, Moscow, Russia, and Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany

Search for other papers by V. M. Gryanik in
Current site
Google Scholar
PubMed
Close
, and
D. J. Olbers Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany

Search for other papers by D. J. Olbers in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

The authors investigate the spreading stage of the deep ocean convection for a strip-shaped convective region to study the law of spreading and sensitivity of the eddy exchange efficiency parameter to the shape of the region and the background stratification. To simulate this convection process a two-layer quasigeostrophic model is used and the input of buoyancy due to surface cooling is parameterized through creation of pairs of baroclinic point vortices with opposite signs of potential vorticity (hetons) at a constant rate. It is shown that the eddy exchange efficiency parameter for lateral fluxes of potential density out of the convective region is not universal but essentially depends on the shape of the region and the relative layer thicknesses. The horizontal spreading of the potential density anomaly shows a faster than diffusive, quasi-linear dependence on time at moderate values of the surface buoyancy flux. This behavior is due to the specific dynamics of hetons and heton clusters.

Corresponding author address: Dr. Vladimir M. Gryanik, Alfred Wegener Institute for Polar and Marine Research, Bussestr. 24, 27570 Bremerhaven, Germany.

Email: vgyranik@awi-bremerhaven.de

Abstract

The authors investigate the spreading stage of the deep ocean convection for a strip-shaped convective region to study the law of spreading and sensitivity of the eddy exchange efficiency parameter to the shape of the region and the background stratification. To simulate this convection process a two-layer quasigeostrophic model is used and the input of buoyancy due to surface cooling is parameterized through creation of pairs of baroclinic point vortices with opposite signs of potential vorticity (hetons) at a constant rate. It is shown that the eddy exchange efficiency parameter for lateral fluxes of potential density out of the convective region is not universal but essentially depends on the shape of the region and the relative layer thicknesses. The horizontal spreading of the potential density anomaly shows a faster than diffusive, quasi-linear dependence on time at moderate values of the surface buoyancy flux. This behavior is due to the specific dynamics of hetons and heton clusters.

Corresponding author address: Dr. Vladimir M. Gryanik, Alfred Wegener Institute for Polar and Marine Research, Bussestr. 24, 27570 Bremerhaven, Germany.

Email: vgyranik@awi-bremerhaven.de

Save
  • Bretherton, F. P., 1966: Critical layer instability in baroclinic flows. Quart. J. Roy. Meteor. Soc.,92, 325–334.

  • Brickman, D., 1995: Heat flux partitioning in deep-ocean convection. J. Phys. Oceanogr.,25, 2609–2623.

  • Chapman, D., and G. Gawarkiewicz, 1997: Shallow convection and buoyancy equilibration in an idealized coastal polynya. J. Phys. Oceanogr.,27, 555–566.

  • Doronina, T. N., V. M. Gryanik, D. J. Olbers, and T. Warncke, 1998:A 3D heton mechanism of lateral spreading in localized convection in a rotating stratified fluid. Rep. 87, Alfred-Wegener-Institut für Polar- und Meeresforschung (AWI)—Berichte aus dem Fachbereich Physic, 75 pp. [Available from Alfred-Wegener-Institut für Polar- und Meeresforachung (AWI), D 27586 Bremerhaven, Germany.].

  • Gascard, J.-C., and R. A. Clarke, 1983: The formation of Labrador Sea Water. Part II: Mesoscale and smaller-scale processes. J. Phys. Oceanogr.,13, 1779–1797.

  • Gent, P., and J. McWilliams, 1990: Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr.,20, 150–155.

  • Green, J. S., 1970: Transfer properties of the large-scale eddies and the general circulation of the atmosphere. Quart. J. Roy. Meteor. Soc.,96, 157–185.

  • Griffiths, R. W., and E. J. Hopfinger, 1986: Experiments with baroclinic vortex pairs in a rotating fluid. J. Fluid Mech.,173, 501–518.

  • Gryanik, V. M., 1983a: Dynamics of singular geostrophic vortices in a two-layer model of the atmosphere (ocean). Izv. Atmos. Ocean Phys.,19, 171–179.

  • ——, 1983b: Dynamics of localized vortex perturbations “vortex charges” in a baroclinic fluid. Izv. Atmos. Ocean Phys.,19(5), 347–352.

  • ——, and M. V. Tevs, 1989: Dynamics of singular geostrophic vortices in a N-layer model of the atmosphere (ocean). Izv. Atmos. Ocean Phys.,25(3), 179–188.

  • ——, and ——, 1991: Dynamics of singular geostrophic vortices near critical points of currents in a N-layer model of the atmosphere (ocean). Izv. Atmos. Ocean Phys.,27(7), 517–526.

  • ——, and ——, 1997: Dynamics and energetics of heton interactions in linearly and exponentially stratified media. Izv. Atmos. Ocean Phys.,33, 419–433.

  • ——, T. N. Doronina, D. J. Olbers, and T. Warncke, 2000: The theory of 3D hetons and vortex-dominated spreading in a localized turbulent convection in a fast rotating stratified fluid. J. Fluid Mech.,423, 71–125.

  • Hogg, N. G., and H. M. Stommel, 1985a: The heton, an elementary interaction between discrete baroclinic geostrophic vortices, and its implications concerning eddy heat-flow. Proc. Roy. Soc. London Ser. A,397, 1–20.

  • ——, and ——, 1985b: Hetonic explosions: The breakup and spread of warm pools as explained by baroclinic point vortices. J. Atmos. Sci.,42, 1465–1476.

  • Hopfinger, E. J., and G. J. F. van Heijst, 1993: Vortices in rotating fluids. Ann. Rev. Fluid Mech.,25, 241–289.

  • Isichenko, M. B., 1992: Percolation, statistical topography, and transport in random media. Rev. Mod. Phys.,64, 961–1043.

  • Jones, H., and J. Marshall, 1993: Convection with rotation in a neutral ocean: A study of deep-ocean convection. J. Phys. Oceanogr.,23, 1009–1039.

  • Käse, R. H., 1998: Modeling of the oceanic mixed layer and effects of deep convection. Buoyant Convection in Geophysical Flow, E. J. Plate et al., Eds., Kluwer, 157–183.

  • Klinger, B. A., and J. Marshall, 1995: Regimes and scaling laws for rotating deep convection in the ocean. Dyn. Atmos. Oceans,21, 227–256.

  • Legg, S., and J. Marshall, 1993: A heton model of the spreading stage of open-ocean deep convection. J. Phys. Oceanogr.,23, 1040–1056.

  • ——, and ——, 1996: The influence of the ambient flow on thespreading of convected water masses. J. Mar. Res.,56, 107–139.

  • ——, H. Jones, and M. Visbeck, 1996: A heton perspective of baroclinic eddy transfer in localized open-ocean deep convection. J. Phys. Oceanogr.,26, 2251–2266.

  • Marshall, J., and F. Schott, 1999: Open-ocean convection: Observations, theory and models. Rev. Geophys.,37, 1–64.

  • Maxworthy, T., and S. Narimousa, 1994: Unsteady turbulent convection into a homogeneous rotating fluid, with oceanographic applications. J. Phys. Oceanogr.,24, 865–887.

  • Narimousa, S., 1998: Turbulent convection into a linearly stratified fluid: The generation of “subsurface anticyclones.” J. Fluid Mech.,354, 101–121.

  • Pedlosky, J., 1979: Geophysical Fluid Dynamics. Springer-Verlag, 625 pp.

  • ——, 1985: The instability of continuous heton clouds. J. Atmos. Sci.,42, 1477–1486.

  • Raasch, S., and D. Etling, 1991: Numerical simulation of rotating turbulent thermal convection. Beitr. Phys. Atmos.,64, 185–199.

  • ——, and ——, 1998: Modeling deep ocean convection: Large eddy simulation in comparison with laboratory experiments. J. Phys. Oceanogr.,28, 1786–1802.

  • Sander, J., D. Wolf-Gladrow, and D. Olbers, 1995: Numerical studies of open ocean deep convection. J. Geophys. Res.,100 (C10), 20 579–20 600.

  • Schott, F., and K. D. Leaman, 1991: Observations with moored acoustic Doppler current profilers in the convective regime in the Golfe du Lion. J. Phys. Oceanogr.,21, 558–574.

  • Send, U., and J. C. Marshall, 1995: Integral effects of deep convection. J. Phys. Oceanogr.,25, 855–872.

  • Sokolovskiy, M. A., 1989: Head-on collisions of distributed hetons. Trans. (Doklady) USSR Acad. Sci.,306, 215–217.

  • ——, and J. Verron, 2000: Finite core hetons: Stability and interactions. J. Fluid. Mech.,423, 127–154.

  • Stommel, H., A. D. Voorhis, and D. Webb, 1971: Submarine clouds in the deep ocean. Amer. Sci.,59, 716–723.

  • Stone, P., 1972: A simplified radiative-dynamical model for the static stability of rotating atmospheres. J. Atmos. Sci.,29, 405–418.

  • Valcke, S., and J. Verron, 1993: On interactions between two finite-core hetons. Phys. Fluids,A5, 2058–2060.

  • Visbeck, M., J. Fisher, and F. Schott, 1995: Preconditioning the Greenland Sea for deep convection: Ice formation and ice drift. J. Geophys. Res.,100, 18 489–18 502.

  • ——, J. Marshall, and H. Jones, 1996: Dynamics of isolated convective regions in oceans. J. Phys. Oceanogr.,26, 1721–1734.

  • ——, ——, T. Haine, and M. Spall, 1997: Specification of eddy transfer coefficients in coarse-resolution ocean circulation models. J. Phys. Oceanogr.,27, 381–402.

  • Whitehead, J. A., J. Marshall, and G. E. Hufford, 1996: Localized convection in rotating stratified fluid. J. Geophys. Res.,101 (C10), 25 705–25 721.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 280 105 0
PDF Downloads 36 12 0