• Avicola, G., , and P. Huq, 2002: Scaling analysis for the interaction between a buoyant coastal current and the continental shelf: Experiments and observations. J. Phys. Oceanogr., 32 , 32333248.

    • Search Google Scholar
    • Export Citation
  • Beardsley, R. C., , R. Limeburner, , H. Yu, , and G. A. Cannon, 1985: Discharge of the Changjiang (Yangtze River) into the East China Sea. Cont. Shelf Res., 4 , 5776.

    • Search Google Scholar
    • Export Citation
  • Blumberg, A. F., , and G. L. Mellor, 1987: A description of a three-dimensional coastal ocean circulation model. Three-Dimensional Coastal Ocean Models, N. S. Heaps, Ed., Coastal and Estuarine Sciences Series, Vol. 4, Amer. Geophys. Union, 1–16.

    • Search Google Scholar
    • Export Citation
  • Brink, K. H., 1991: Coastal-trapped waves and wind-driven currents over the continental shelf. Annu. Rev. Fluid Mech., 23 , 389412.

  • Burchard, H., , F. Janssen, , K. Bolding, , and L. Umlauf, 2009: Model simulations of dense bottom currents in the western Baltic Sea. Cont. Shelf Res., 29 , 205220.

    • Search Google Scholar
    • Export Citation
  • Cenedese, C., , J. A. Whitehead, , T. A. Ascarelli, , and M. Ohiwa, 2004: A dense current flowing down a sloping bottom in a rotating fluid. J. Phys. Oceanogr., 34 , 188203.

    • Search Google Scholar
    • Export Citation
  • Chao, S-Y., , and W. C. Boicourt, 1986: Onset of estuarine plume. J. Phys. Oceanogr., 16 , 21372149.

  • Chapman, D. C., , and S. J. Lentz, 1994: Trapping of coastal density front by the bottom boundary layer. J. Phys. Oceanogr., 24 , 14641479.

    • Search Google Scholar
    • Export Citation
  • Csanady, G. T., 1978: The arrested topographic wave. J. Phys. Oceanogr., 8 , 4762.

  • Fong, D. A., 1998: Dynamics of freshwater plumes: Observations and numerical modeling of the wind-forced response and alongshore freshwater transport. Ph.D. dissertation, Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 172 pp.

  • Fong, D. A., , and W. R. Geyer, 2002: The alongshore transport of freshwater in a surface-trapped river plume. J. Phys. Oceanogr., 32 , 957972.

    • Search Google Scholar
    • Export Citation
  • Framiñan, M., 2005: On the physics, circulation, and exchanges processes of the Rio de la Plata estuary and adjacent shelf. Ph.D. Dissertation, University of Miami, 486 pp.

  • Garvine, R. W., 1999: Penetration of buoyant coastal discharge onto the continental shelf: A numerical model experiment. J. Phys. Oceanogr., 29 , 18921909.

    • Search Google Scholar
    • Export Citation
  • Garvine, R. W., 2001: The impact of model configuration in studies of buoyant coastal discharge. J. Mar. Res., 59 , 193225.

  • Guo, X., , and A. Valle-Levinson, 2007: Tidal effects on estuarine circulation and outflow plume in the Chesapeake Bay. Cont. Shelf Res., 27 , 2042.

    • Search Google Scholar
    • Export Citation
  • Kourafalou, V. H., , L-Y. Oey, , J. D. Wang, , and T. N. Lee, 1996: The fate of river discharge on the continental shelf. 1. Modeling the river plume and inner shelf coastal current. J. Geophys. Res., 101 , 34153434.

    • Search Google Scholar
    • Export Citation
  • Kubokawa, A., 1991: On the behavior of outflows with low potential vorticity from a sea strait. Tellus, 43A , 168176.

  • Matano, R. P., , and E. D. Palma, 2008: On the upwelling of downwelling currents. J. Phys. Oceanogr., 38 , 24822500.

  • Matano, R. P., , and E. D. Palma, 2010: The spindown of bottom-trapped plumes. J. Phys. Oceanogr., 40 , 16511658.

  • McCreary, J. P., , S. Zhang, , and S. R. Shetye, 1997: Coastal circulation driven by river outflow in a variable-density 1½-layer model. J. Geophys. Res., 102 , 1553515554.

    • Search Google Scholar
    • Export Citation
  • Mellor, G. L., , and T. Yamada, 1982: Development of a turbulent closure model for geophysical fluid problems. Rev. Geophys. Space Phys., 20 , 851868.

    • Search Google Scholar
    • Export Citation
  • Murty, V. S. N., , Y. V. B. Sarma, , D. P. Rao, , and C. S. Murty, 1992: Water characteristics, mixing and circulation in the Bay of Bengal during southwest monsoons. J. Mar. Res., 50 , 207228.

    • Search Google Scholar
    • Export Citation
  • Narayanan, C., , and R. W. Garvine, 2002: Large scale buoyancy driven circulation on the continental shelf. Dyn. Atmos. Oceans, 36 , 125152.

    • Search Google Scholar
    • Export Citation
  • Nof, D., , and T. Pichevin, 2001: The ballooning of outflows. J. Phys. Oceanogr., 31 , 30453058.

  • Palma, E. D., , and R. P. Matano, 1998: On the implementation of open boundary conditions to a general circulation model: The barotropic mode. J. Geophys. Res., 103 , 13191341.

    • Search Google Scholar
    • Export Citation
  • Palma, E. D., , and R. P. Matano, 2000: On the implementation of open boundary conditions for a general circulation model: The three-dimensional case. J. Geophys. Res., 105 , (C4). 86058627.

    • Search Google Scholar
    • Export Citation
  • Pichevin, T., , and D. Nof, 1997: The momentum imbalance paradox. Tellus, 49A , 298319.

  • Piola, A. R., , S. I. Romero, , and U. Zajaczkovski, 2008: Space-time variability of the Plata plume inferred from ocean color. Cont. Shelf Res., 28 , 15561567.

    • Search Google Scholar
    • Export Citation
  • Shaw, P. T., , and G. T. Csanady, 1983: Self-advection of density perturbations on a sloping continental shelf. J. Phys. Oceanogr., 13 , 769782.

    • Search Google Scholar
    • Export Citation
  • Smolarkiewicz, P. K., , and W. W. Grabowski, 1990: The multi-dimensional positive definite advection transport algorithm: Nonoscillatory option. J. Comput. Phys., 86 , 355375.

    • Search Google Scholar
    • Export Citation
  • Weingartner, T. J., , S. Danielson, , Y. Sasaki, , V. Pavlov, , and M. Kulakov, 1999: The Siberian Coastal Current: A wind- and buoyancy-forced Arctic coastal current. J. Geophys. Res., 104 , 2969729713.

    • Search Google Scholar
    • Export Citation
  • Woods, A. W., , and R. C. Beardsley, 1988: On the barotropic discharge of a homogeneous fluid onto a continental shelf. Cont. Shelf Res., 8 , 307327.

    • Search Google Scholar
    • Export Citation
  • Yankovsky, A. E., 2000: The cyclonic turning and propagation of buoyant coastal discharge along the shelf. J. Mar. Res., 58 , 585607.

  • Yankovsky, A. E., , and D. C. Chapman, 1997: A simple theory for the fate of buoyant coastal discharges. J. Phys. Oceanogr., 27 , 13861401.

    • Search Google Scholar
    • Export Citation
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The Upstream Spreading of Bottom-Trapped Plumes

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  • 1 College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon
  • | 2 Departamento de Fisica, Universidad Nacional del Sur, and Instituto Argentino de Oceanografía (CONICET), Bahia Blanca, Argentina
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Abstract

It is well known that numerical simulations of freshwater discharges produce plumes that spread in the direction opposite to that of the propagation of coastally trapped waves (the upstream direction). The lack of a theory explaining these motions in unforced environments deemed the numerical results suspect. Thus, it became a common practice in numerical studies to add a downstream mean flow to arrest the development of the upstream perturbation. This approach is generally unjustified, and it remains a matter of interest to determine if the upstream displacement produced by models is a geophysical phenomenon or a consequence of erroneous assumptions in the model setup. In this article, the results of highly idealized numerical experiments are used to investigate these matters. It is shown that this phenomenon is associated with the geostrophic adjustment of the discharge and that upstream motion is endemic to the baroclinic structure of bottom-trapped plumes. It is also shown that downstream displacements are generated by the cross-shelf barotropic pressure gradient generated by the propagation of coastally trapped waves. Sensitivity experiments indicate that the speed of upstream propagation and the density structure of the plume are affected by bottom friction, the slope of the bottom, and the magnitude of the density anomaly. Bottom friction in particular slows down the progression of the plume and changes its density structure, producing a more homogeneous downstream region and a more stratified upstream region.

Corresponding author address: Ricardo P. Matano, College of Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Administration Building, Corvallis, OR 97331-5503. Email: rmatano@coas.oregonstate.edu

Abstract

It is well known that numerical simulations of freshwater discharges produce plumes that spread in the direction opposite to that of the propagation of coastally trapped waves (the upstream direction). The lack of a theory explaining these motions in unforced environments deemed the numerical results suspect. Thus, it became a common practice in numerical studies to add a downstream mean flow to arrest the development of the upstream perturbation. This approach is generally unjustified, and it remains a matter of interest to determine if the upstream displacement produced by models is a geophysical phenomenon or a consequence of erroneous assumptions in the model setup. In this article, the results of highly idealized numerical experiments are used to investigate these matters. It is shown that this phenomenon is associated with the geostrophic adjustment of the discharge and that upstream motion is endemic to the baroclinic structure of bottom-trapped plumes. It is also shown that downstream displacements are generated by the cross-shelf barotropic pressure gradient generated by the propagation of coastally trapped waves. Sensitivity experiments indicate that the speed of upstream propagation and the density structure of the plume are affected by bottom friction, the slope of the bottom, and the magnitude of the density anomaly. Bottom friction in particular slows down the progression of the plume and changes its density structure, producing a more homogeneous downstream region and a more stratified upstream region.

Corresponding author address: Ricardo P. Matano, College of Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Administration Building, Corvallis, OR 97331-5503. Email: rmatano@coas.oregonstate.edu

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