Statistics of Shear and Turbulent Dissipation Profiles in Random Internal Wave Fields

Gregg, Michael C.; Seim, Harvey; Percival, Donald B.

doi:10.1175/1520-0485(1993)023<1777:sosatd>2.0.co;2

Cited by 56 publications

(51 citation statements)

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“…Although the spatial and temporal resolution of these datasets is too coarse to estimate this directly, the intermittency of shear production predicted by the model is consistent with estimates of dissipation of turbulent kinetic energy made with microstructure instruments (e.g., Gregg et al 1993). Furthermore, these spikes in shear occurred without a wind stress rotating at the local inertial frequency and so may be more widely prevalent than the resonant case.…”

Section: Discussionsupporting

confidence: 75%

Shear at the Base of the Oceanic Mixed Layer Generated by Wind Shear Alignment

Brannigan

Lenn

Rippeth

et al. 2013

Journal of Physical Oceanography

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Observations are used to evaluate a simple theoretical model for the generation of near-inertial shear spikes at the base of the open ocean mixed layer when the upper ocean displays a two-layer structure. The model predicts that large changes in shear squared can be produced by the alignment of the wind and shear vectors. A climatology of stratification and shear variance in Drake Passage is presented, which shows that these assumptions are most applicable to summer, fall, and spring but are not highly applicable to winter. Temperature, salinity, and velocity data from a high spatial resolution cruise in Drake Passage show that the model does not predict all large changes in shear variance; the model is most effective at predicting changes in shear squared when it arises owing to near-inertial wind-driven currents without requiring a rotating resonant wind stress. The model is also more effective where there is a uniform mixed layer above a strongly stratified transition layer. Rotary spectral and statistical analysis of an additional 242 Drake Passage transects from 1999 to 2011 confirmed the presence of this shear-spiking mechanism, particularly in summer, spring, and fall when stratification is stronger.

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Section: Discussionsupporting

confidence: 75%

Shear at the Base of the Oceanic Mixed Layer Generated by Wind Shear Alignment

Brannigan

Lenn

Rippeth

et al. 2013

Journal of Physical Oceanography

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“…The question of the appropriate way to average such an intermittent variable as or K z using experimentally limited number of samples has long been debated (Baker and Gibson, 1987;Gregg et al, 1993;Davis, 1996;Gargett, 1999). We use here three estimates of the mean: (1) a simple arithmetic mean as suggested by Gregg et al (1993), Davis (1996); (2) a geometric mean which is sometimes used in order to reduce the dispersion of dissipation rate data (Gargett, 1999;Smyth et al, 1997); and (3) a maximum likelihood estimate (MLE, Priestley, 1981) of the mean dissipation following Baker and Gibson (1987).…”

Section: Dissipation Measurements In the Upper Oceanicmentioning

confidence: 99%

“…We use here three estimates of the mean: (1) a simple arithmetic mean as suggested by Gregg et al (1993), Davis (1996); (2) a geometric mean which is sometimes used in order to reduce the dispersion of dissipation rate data (Gargett, 1999;Smyth et al, 1997); and (3) a maximum likelihood estimate (MLE, Priestley, 1981) of the mean dissipation following Baker and Gibson (1987). In this last case a lognormal distribution for is assumed and the mean dissipation rate is given by:…”

Section: Dissipation Measurements In the Upper Oceanicmentioning

confidence: 99%

Characterization of turbulence from a fine-scale parameterization and microstructure measurements in the Mediterranean Sea during the BOUM experiment

Cuypers

Bouruet‐Aubertot

Marec³

et al. 2012

Biogeosciences

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Abstract.One of the main purposes of the BOUM experiment was to find evidence of the possible impact of submesoscale dynamics on biogeochemical cycles. To this aim physical as well as biogeochemical data were collected along a zonal transect through the western and eastern basins of the Mediterranean Sea. Along this transect 3-day fixed point stations were performed within anticyclonic eddies during which microstructure measurements of the temperature gradient were collected over the top 100 m of the water column. We focus here on the characterization of turbulent mixing. The analysis of microstructure measurements revealed a high level of turbulent kinetic energy (TKE) dissipation rate in the seasonal pycnocline and a moderate level below with mean values of the order of 10 −6 W kg −1 and 10 −8 W kg −1 , respectively. The Gregg Henyey (Gregg, 1989) fine-scale parameterization of TKE dissipation rate produced by internal wave breaking, and adapted here following Polzin et al. (1995) to take into account the strain to shear ratio, was first compared to these direct measurements with favorable results. The parameterization was then applied to the whole data set. Within the eddies, a significant increase of dissipation at the top and base of eddies associated with strong near-inertial waves is observed. Vertical turbulent diffusivity is increased both in these regions and in the weakly stratified eddy core. The stations collected along the East-West transect provide an overview of parameterized TKE dissipation rates and vertical turbulent diffusivity over a latitudinal section of the Mediterranean Sea. Strong TKE dissipation rates are found within the first 500 m and up to 1500 m above the bottom. Close to the bottom where the stratification is weak, the inferred vertical turbulent diffusivity can reach K z 10 −3 m 2 s −1 and may therefore have a strong impact on the upward diffusive transport of deep waters masses.

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“…The locations of previous microstructure measurements [ Gregg et al, 1073Gregg et al, , 1993Gregg, 1977Gregg, , 1998 …”

Section: Tropical Cyclone In the Westernmentioning

confidence: 99%

Spatial and temporal distribution of the wind‐induced internal wave energy available for deep water mixing in the North Pacific

Nagasawa¹,

Niwa²,

Hibiya³

2000

J. Geophys. Res.

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Statistics of Shear and Turbulent Dissipation Profiles in Random Internal Wave Fields

Cited by 56 publications

References 0 publications

Shear at the Base of the Oceanic Mixed Layer Generated by Wind Shear Alignment

Shear at the Base of the Oceanic Mixed Layer Generated by Wind Shear Alignment

Characterization of turbulence from a fine-scale parameterization and microstructure measurements in the Mediterranean Sea during the BOUM experiment

Spatial and temporal distribution of the wind‐induced internal wave energy available for deep water mixing in the North Pacific

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