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Geostrophic Turbulence over a Slope

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  • 1 Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
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Abstract

The authors examine freely evolving geostrophic turbulence, in two layers over a linearly sloping bottom. The initial flow is surface trapped and subdeformation scale. In all cases with a slope, two components are found: a collection of surface vortices, and a bottom-intensified flow that has zero surface potential vorticity. The rate of spinup and the scale of the bottom flow depend on Λ ≡ F2U1/β2, which measures the importance of interfacial stretching to the bottom slope, with small values of Λ corresponding to a slow spinup and stronger along-isobath anisotropy. The slope also affects the mean size of the surface vortices, through the dispersal of flow at depth and by altering vortex stability. This too can be characterized in terms of the parameter, Λ.

Corresponding author address: Joe LaCasce, Woods Hole Oceanographic Institution, M.S. 29, Woods Hole, MA 02543.

Email: jlacasce@whoi.edu

Abstract

The authors examine freely evolving geostrophic turbulence, in two layers over a linearly sloping bottom. The initial flow is surface trapped and subdeformation scale. In all cases with a slope, two components are found: a collection of surface vortices, and a bottom-intensified flow that has zero surface potential vorticity. The rate of spinup and the scale of the bottom flow depend on Λ ≡ F2U1/β2, which measures the importance of interfacial stretching to the bottom slope, with small values of Λ corresponding to a slow spinup and stronger along-isobath anisotropy. The slope also affects the mean size of the surface vortices, through the dispersal of flow at depth and by altering vortex stability. This too can be characterized in terms of the parameter, Λ.

Corresponding author address: Joe LaCasce, Woods Hole Oceanographic Institution, M.S. 29, Woods Hole, MA 02543.

Email: jlacasce@whoi.edu

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