Numerical simulations of the internal tide in a submarine canyon

Petruncio, Emil T.; Paduan, Jeffrey D.; Rosenfeld, Leslie K.

doi:10.1016/s1463-5003(02)00002-1

Cited by 38 publications

(43 citation statements)

References 40 publications

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“…Asymmetrical IW generation in a canyon, a major topic here, has already been observed in a numerical model (Petruncio et al 2002). Specifically, modeled internal-tide energy is stronger within the upstream side of the canyon, in the sense of coastaltrapped wave propagation, even when the canyon bathymetry and offshore barotropic tidal forcing are symmetrical with respect to the canyon axis.…”

Section: Introductionsupporting

confidence: 52%

Modeling and Analysis of Internal-Tide Generation and Beamlike Onshore Propagation in the Vicinity of Shelfbreak Canyons

Zhang

Duda

Udovydchenkov

2014

Journal of Physical Oceanography

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A hydrostatic numerical model with alongshore-uniform barotropic M 2 tidal boundary forcing and idealized shelfbreak canyon bathymetries is used to study internal-tide generation and onshore propagation. A control simulation with Mid-Atlantic Bight representative bathymetry is supported by other simulations that serve to identify specific processes. The canyons and adjacent slopes are transcritical in steepness with respect to M 2 internal wave characteristics. Although the various canyons are symmetrical in structure, barotropicto-baroclinic energy conversion rates C y are typically asymmetrical within them. The resulting onshorepropagating internal waves are the strongest along beams in the horizontal plane, with the stronger beam in the control simulation lying on the side with higher C y . Analysis of the simulation results suggests that the cross-canyon asymmetrical C y distributions are caused by multiple-scattering effects on one canyon side slope, because the phase variation in the spatially distributed internal-tide sources, governed by variations in the orientation of the bathymetry gradient vector, allows resonant internal-tide generation. A less complex, semianalytical, modal internal wave propagation model with sources placed along the critical-slope locus (where the M 2 internal wave characteristic is tangent to the seabed) and variable source phasing is used to diagnose the physics of the horizontal beams of onshore internal wave radiation. Model analysis explains how the cross-canyon phase and amplitude variations in the locally generated internal tides affect parameters of the internal-tide beams. Under the assumption that strong internal tides on continental shelves evolve to include nonlinear wave trains, the asymmetrical internal-tide generation and beam radiation effects may lead to nonlinear internal waves and enhanced mixing occurring preferentially on one side of shelfbreak canyons, in the absence of other influencing factors.

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Section: Introductionsupporting

confidence: 52%

Modeling and Analysis of Internal-Tide Generation and Beamlike Onshore Propagation in the Vicinity of Shelfbreak Canyons

Zhang

Duda

Udovydchenkov

2014

Journal of Physical Oceanography

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“…Two models of the well studied Monterey Bay Canyon have been done. The earlier model captured much of the qualitative structure of internal tides in the canyon including up-canyon energy propagation and bottomintensified currents within the canyon but simulated velocities were too small by almost an order of magnitude (Petruncio et al, 2002). The most recent study used non-hydrostatic dynamics and included the along-coast tidal component.…”

Section: Enhanced Internal Tides and Mixing In Canyonsmentioning

confidence: 99%

A review of the role of submarine canyons in deep-ocean exchange with the shelf

2009

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Abstract. Cross shelf-break exchange is limited by the tendency of geostrophic flow to follow bathymetric contours, not cross them. However, small scale topography, such as canyons, can reduce the local lengthscale of the flow and increase the local Rossby number. These higher Rossby numbers mean the flow is no longer purely geostrophic and significant cross-isobath flow can occur. This cross-isobath flow includes both upwelling and downwelling due to wind-driven shelf currents and the strong cascading flows of dense shelfwater into the ocean. Tidal currents usually run primarily parallel to the shelf-break topography. Canyons cut across these flows and thus are often regions of generation of strong baroclinic tides and internal waves. Canyons can also focus internal waves. Both processes lead to greatly elevated levels of mixing. Thus, through both advection and mixing processes, canyons can enhance Deep Ocean Shelf Exchange. Here we review the state of the science describing the dynamics of the flows and suggest further areas of research, particularly into quantifying fluxes of nutrients and carbon as well as heat and salt through canyons.

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“…It is the largest submarine canyon along the west coast of the United States and has been the focus of several internal tide observational programs (Key, 1999;Kunze et al, 2002;Johnston et al, 2011;Kunze et al, 2012) and numerical modelling studies (Petruncio et al, 2002;Jachec et al, 2006;Wang et al, 2009;Kang and Fringer, 2012). In stratified seas, barotropic (surface) tidal flow across the sloping topography typical of submarine canyons can generate internal tides (internal gravity waves with tidal frequencies) by vertically displacing density surfaces (Bell, 1975;Baines, 1982).…”

Section: Introductionmentioning

confidence: 99%

Transition from partly standing to progressive internal tides in Monterey Submarine Canyon

Hall

Alford

Carter

et al. 2014

Deep Sea Research Part II: Topical Studies in Oceanography

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Monterey Submarine Canyon is a large, sinuous canyon off the coast of California, the upper reaches of which were the subject of an internal tide observational program using moored profilers and upward-looking moored ADCPs. The mooring observations measured a near-surface stratification change in the upper canyon, likely caused by a seasonal shift in the prevailing wind that favoured coastal upwelling. This change in near-surface stratification caused a transition in the behaviour of the internal tide in the upper canyon from a partly standing wave during pre-upwelling conditions to a progressive wave during upwelling conditions. Using a numerical model, we present evidence that either a partly standing or a progressive internal tide can be simulated in the canyon, simply by changing the initial stratification conditions in accordance with the observations. The mechanism driving the transition is a dependence of down-canyon (supercritical) internal tide reflection from the canyon floor and walls on the depth of maximum stratification. During pre-upwelling conditions, the main pycnocline extends down to 200 m (below the canyon rim) resulting in increased supercritical reflection of the up-canyon propagating internal tide back down the canyon. The large up-canyon and smaller down-canyon progressive waves are the two components of the partly standing wave. During upwelling conditions, the pycnocline shallows to the upper 50 m of the watercolumn (above the canyon rim) resulting in decreased supercritical reflection and allowing the up-canyon progressive wave to dominate.

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Numerical simulations of the internal tide in a submarine canyon

Cited by 38 publications

References 40 publications

Modeling and Analysis of Internal-Tide Generation and Beamlike Onshore Propagation in the Vicinity of Shelfbreak Canyons

Modeling and Analysis of Internal-Tide Generation and Beamlike Onshore Propagation in the Vicinity of Shelfbreak Canyons

A review of the role of submarine canyons in deep-ocean exchange with the shelf

Transition from partly standing to progressive internal tides in Monterey Submarine Canyon

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