Author

# Chris Garrett

Other affiliations: University of British Columbia, Dalhousie University, University of California, Los Angeles ...read more

Bio: Chris Garrett is an academic researcher from University of Victoria. The author has contributed to research in topics: Internal wave & Mixed layer. The author has an hindex of 56, co-authored 133 publications receiving 10737 citations. Previous affiliations of Chris Garrett include University of British Columbia & Dalhousie University.

Topics: Internal wave, Mixed layer, Buoyancy, Geostrophic wind, Heat flux

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TL;DR: In this article, a revised model for the distribution of internal wave energy in wave number frequency space is presented, guided by the following measurements: moored spectra and moored coherences for horizontal and vertical separations.

Abstract: We present a revised model for the distribution of internal wave energy in wave number frequency space. The model is empirical, guided by the following measurements: moored spectra and moored coherences for horizontal and vertical separations (MS, MHC, MVC as functions of frequency), towed spectra and towed vertical and time-lagged coherences (TS, TVC, TLC as functions of horizontal wave number), and dropped spectra and dropped horizontal and lagged coherences (DS, DHC, DLC as functions of vertical wave number). Measurements are available for all but TLC and DHC. There is some indication of universality, suggesting perhaps a saturation limit.

860 citations

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TL;DR: In this paper, a model E(α, ω) α μ−1ω−p+1(ω 2−ω i 2)−++ for the distribution of internal wave energy in horizontal wavenumber, frequency-space, with wavenumbers α extending to some upper limit μ(ω) α ω r-1 (ω 2 −ω i 1 2)½, and frequency ω extending from the inertial frequency i to the local Vaisala frequency n(y).

Abstract: We have contrived a model E(αω) α μ−1ω−p+1(ω 2−ω i 2)−+ for the distribution of internal wave energy in horizontal wavenumber, frequency-space, with wavenumber α extending to some upper limit μ(ω) α ω r-1 (ω 2−ω i 2)½, and frequency ω extending from the inertial frequency ω i to the local Vaisala frequency n(y). The spectrum is portrayed as an equivalent continuum to which the modal structure (if it exists) is not vital. We assume horizontal isotropy, E(α, ω) = 2παE(α1, α2, ω), with α1, α2 designating components of α. Certain moments of E(α1, α2, ω) can be derived from observations. (i) Moored (or freely floating) devices measuring horizontal current u(t), vertical displacement η(t),…, yield the frequency spectra F (u,η,…)(ω) = ∫∫ (U 2, Z 2,…)E(α1, ∞2, ω) dα1 dα2, where U, Z,… are the appropriate wave functions. (ii) Similarly towed measurements give the wavenumber spectrum F (…)(α1) = ∫∫… dα2 dω. (iii) Moored measurements horizontally separated by X yield the coherence spectrum R(X, ω) which is ...

783 citations

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TL;DR: In this article, it was shown that most of the energy flux is associated with low modes that propagate away from the generation region, and that intensity beams of internal tidal energy are expected near critical slopes, bottom slopes equal to the ray slope.

Abstract: Internal tides are internal gravity waves generated in stratified waters by the interaction of barotropic tidal currents with variable bottom topography. They play a role in dissipating tidal energy and lead to mixing in the deep ocean. Key dimensionless parameters governing their generation include the tidal excursion compared with the scale of the topography, the bottom slope compared with the angle at which rays of internal waves of tidal frequency propagate, and the height of the topography compared with the depth of the ocean. Recent theoretical developments for parts of this parameter space particularly relevant to the deep ocean show that most of the energy flux is associated with low modes that propagate away from the generation region. For isolated features this energy flux is not strongly dependent on the bottom slope. Intense beams of internal tidal energy are expected near “critical slopes," bottom slopes equal to the ray slope, and lead to local mixing.

602 citations

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TL;DR: In this article, internal wave theory is used to examine the generation, radiation, and energy dissipation of internal tides in the deep ocean and estimates of vertical energy flux based on a previously developed model are adjusted to account for the influence of finite depth, varying stratification, and two-dimensional topography.

Abstract: Internal wave theory is used to examine the generation, radiation, and energy dissipation of internal tides in the deep ocean. Estimates of vertical energy flux based on a previously developed model are adjusted to account for the influence of finite depth, varying stratification, and two-dimensional topography. Specific estimates of energy flux are made for midocean ridge topography. Weakly nonlinear theory is applied to the wave generation at idealized topography to examine finite amplitude corrections to the linear theory. Most internal tide energy is generated at low modes associated with spatial scales from roughly 20 to 100 km. The Richardson number of the radiated internal tide typically exceeds unity for these motions, and so direct shear instability of the generated waves is not the dominant energy transfer mechanism. It also seems that wave–wave interactions are ineffective at transferring energy from the large wavelengths that dominate the energy flux. Instead, it appears that most of ...

415 citations

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TL;DR: Using the Levitus climatology, the authors showed that 2.1 TW (terawatts) is required to maintain the global abyssal density distribution against 30 Sverdrups of deep water formation.

1,958 citations

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TL;DR: In particular, small-scale mixing processes are necessary to resupply the potential energy removed in the interior by the overturning and eddy-generating process as discussed by the authors, and it is shown that over most of the ocean significant vertical mixing is confined to topographically complex boundary areas implies a potentially radically different interior circulation than is possible with uniform mixing.

Abstract: ▪ AbstractThe coexistence in the deep ocean of a finite, stable stratification, a strong meridional overturning circulation, and mesoscale eddies raises complex questions concerning the circulation energetics. In particular, small-scale mixing processes are necessary to resupply the potential energy removed in the interior by the overturning and eddy-generating process. A number of lines of evidence, none complete, suggest that the oceanic general circulation, far from being a heat engine, is almost wholly governed by the forcing of the wind field and secondarily by deep water tides. In detail however, the budget of mechanical energy input into the ocean is poorly constrained. The now inescapable conclusion that over most of the ocean significant “vertical” mixing is confined to topographically complex boundary areas implies a potentially radically different interior circulation than is possible with uniform mixing. Whether ocean circulation models, either simple box or full numerical ones, neither explic...

1,356 citations

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TL;DR: A considerable amount of work has been made and definite results obtained about the circulation in the Western Mediterranean Sea during the last decade as mentioned in this paper, mainly in the south where all water masses appear to flow anticlockwise along the continental slope, as they do everywhere else in the sea.

1,103 citations

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TL;DR: Ocean microstructure data show that turbulent mixing in the deep Brazil Basin of the South Atlantic Ocean is weak at all depths above smooth abyssal plains and the South American Continental Rise, which implies that abyssal circulations have complex spatial structures that are linked to the underlying bathymetry.

Abstract: Ocean microstructure data show that turbulent mixing in the deep Brazil Basin of the South Atlantic Ocean is weak at all depths above smooth abyssal plains and the South American Continental Rise. The diapycnal diffusivity there was estimated to be less than or approximately equal to 0.1 x 10(-4) meters squared per second. In contrast, mixing rates are large throughout the water column above the rough Mid-Atlantic Ridge, and the diffusivity deduced for the bottom-most 150 meters exceeds 5 x 10(-4) meters squared per second. Such patterns in vertical mixing imply that abyssal circulations have complex spatial structures that are linked to the underlying bathymetry.

1,038 citations

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28 Dec 1987

TL;DR: Tidal Patterns Meteorological and Other Non-tidal Disturbances Some Definitions of Common Terms Basic Statistics of Tides as Time Series Observations and Data Reduction Forces Analysis and Prediction Tidal Dynamics Biology: Some Tidal Influences Filters for Tidal Time Series Response Analysis Inputs and Theory Analysis of Currents Theoretical Tidal dynamics Legal Definitions in the Coastal Zone as discussed by the authors.

Abstract: Introduction: Early Ideas and Observations Tidal Patterns Meteorological and Other Non-tidal Disturbances Some Definitions of Common Terms Basic Statistics of Tides as Time Series Observations and Data Reduction Forces Analysis and Prediction Tidal Dynamics Biology: Some Tidal Influences Filters for Tidal Time Series Response Analysis Inputs and Theory Analysis of Currents Theoretical Tidal Dynamics Legal Definitions in the Coastal Zone

987 citations