Oceanic Isopycnal Slope Spectra. Part II: Turbulence

Klymak, Jody M.; Moum, James N.

doi:10.1175/jpo3074.1

Cited by 68 publications

(110 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Average slope from the open ocean samples between 500-125 m wavelengths is −0.6 ± 0.1. This is consistent with Klymak and Moum (2007) who suggested that k −0.5 x is a good model for the internal-wave subrange at low horizontal wavenumbers. The relatively elevated spectral level at 1 km wavelength can be attributed to the Aves Ridge and variable local bathymetry.…”

Section: Weak Turbulencesupporting

confidence: 92%

“…The spectral level at scales larger than 1 km suggest a background internal wave activity that might lead to weak turbulent fluxes; however, the existence of the regular structure in the staircase shows that double-diffusive fluxes must dominate. Klymak and Moum (2007) show that the turbulence subrange of isopycnal slope spectra extends to surprisingly large horizontal wavelengths (> 100 m) and can be distinguished with a k 1/3 x slope. In our data set, the slope spectra from the reflections are contaminated by noise at high wavenumbers, dominated by the peak at 50 m wavelength due to shot spacing.…”

Section: Weak Turbulencementioning

confidence: 88%

“…The spectral analysis assumes that the reflection horizons oscillate with the isopycnals, which can be erroneous in the presence of density-compensating thermohaline staircase and intrusions. Following Klymak and Moum (2007) we present the spectra for the horizontal gradient of vertical displacements, i.e. slope spectra, φ ζ x = (2π k x ) 2 φ ζ .…”

Section: Spectral Analysismentioning

confidence: 99%

See 2 more Smart Citations

Seismic imaging of a thermohaline staircase in the western tropical North Atlantic

et al. 2010

View full text Add to dashboard Cite

Abstract. Multichannel seismic data acquired in the Lesser Antilles in the western tropical North Atlantic indicate that the seismic reflection method has imaged an oceanic thermohaline staircase. Synthetic acoustic modeling using measured density and sound speed profiles corroborates inferences from the seismic data. In a small portion of the seismic image, laterally coherent, uniform layers are present at depths ranging from 550-700 m and have a separation of ∼ 20 m, with thicknesses increasing with depth. The reflection coefficient, a measure of the acoustic impedance contrasts across these reflective interfaces, is one order of magnitude greater than background noise. Hydrography sampled in previous surveys suggests that the layers are a permanent feature of the region. Spectral analysis of layer horizons in the thermohaline staircase indicates that internal wave activity is anomalously low, suggesting weak internal waveinduced turbulence. Results from two independent measurements, the application of a finescale parameterization to observed high-resolution velocity profiles and direct measurements of turbulent dissipation rate, confirm these low levels of turbulence. The lack of internal wave-induced turbulence may allow for the maintenance of the staircase or may be due to suppression by the double-diffusive convection within the staircase. Our observations show the potential for seismic oceanography to contribute to an improved understanding of occurrence rates and the geographical distribution of thermohaline staircases, and should thereby improve estimates of vertical mixing rates ascribable to salt fingering in the global ocean.

show abstract

Section: Weak Turbulencesupporting

confidence: 92%

Section: Weak Turbulencementioning

confidence: 88%

Section: Spectral Analysismentioning

confidence: 99%

See 1 more Smart Citation

Seismic imaging of a thermohaline staircase in the western tropical North Atlantic

et al. 2010

View full text Add to dashboard Cite

show abstract

“…The existence of the spectrum (8.15) is not indisputable. A study by Klymak & Moum [148] suggests that the inertial subrange with the Corrsin-Obukhov spectrum extends to horizontal wavenumbers k h smaller than k O by some one or two orders of magnitude. Further discussion along these lines can be found in Riley & Lindborg [15].…”

Section: (D) Horizontal Spectrum Of the Potential Energymentioning

confidence: 99%

An analytical theory of the buoyancy–Kolmogorov subrange transition in turbulent flows with stable stratification

Sukoriansky

Galperin

2013

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

The buoyancy subrange of stably stratified turbulence is defined as an intermediate range of scales larger than those in the inertial subrange. This subrange encompasses the crossover from internal gravity waves (IGWs) to small-scale turbulence. The energy exchange between the waves and small-scale turbulence is communicated across this subrange. At the same time, it features progressive anisotropization of flow characteristics on increasing spatial scales. Despite many observational and computational studies of the buoyancy subrange, its theoretical understanding has been lagging. This article presents an investigation of the buoyancy subrange using the quasi-normal scale elimination (QNSE) theory of turbulence. This spectral theory uses a recursive procedure of small-scale modes elimination based upon a quasi-normal mapping of the velocity and temperature fields using the Langevin equations. In the limit of weak stable stratification, the theory becomes completely analytical and yields simple expressions for horizontal and vertical eddy viscosities and eddy diffusivities. In addition, the theory provides expressions for various one-dimensional spectra that quantify turbulence anisotropization. The theory reveals how the dispersion relation for IGWs is modified by turbulence, thus alleviating many unique waves' features. Predictions of the QNSE theory for the buoyancy subrange are shown to agree well with various data.

show abstract

“…Recent work (Klymak and Moum 2007) has also demonstrated that turbulent mixing rates can be obtained from isopycnal slope spectra for wavenumbers out to greater than 1 /100 m. To obtain the isopycnal slope spectra, it is necessary to measure both the vertical and horizontal temperature and salinity structure with as high as possible resolution. Making these measurements from a towed sampling platform also requires steep trajectories within specific depth bands in order to resolve the necessary horizontal scales.…”

Section: Introductionmentioning

confidence: 99%

Concept Tests for a New Wire Flying Vehicle Designed to Achieve High Horizontal Resolution Profiling in Deep Water

Roman

Hebert

2011

Journal of Atmospheric and Oceanic Technology

View full text Add to dashboard Cite

Efficiently profiling the water column to achieve both high vertical and horizontal resolution from a moving vessel in deep water is difficult. Current solutions, such as CTD tow-yos, moving vessel profilers, and undulating tow bodies, are limited by ship speed or water depth. As a consequence, it is difficult to obtain oceanographic sections with sufficient resolution to identify many relevant scales over the deeper sections of the water column. This paper presents a new concept for a profiling vehicle that slides up and down a towed wire in a controlled manner using the lift created by wing foils. The wings provide a novel low-power method of propulsion along the cable by using the free stream velocity of the wire moving through the water in similar fashion to a sailboat sailing up wind. Scale model tests show a wide range of achievable profiling glide slopes for tow cable angles between vertical and 458, and effective isolation of cable strum vibration from the towed vehicle body. The concept is not depth limited and will offer two-dimensional resolution that meets or exceeds current undulating tow bodies over the full water column. Additionally, this system could be used simultaneously with many other deep towed instrument packages to produce complementary datasets.

show abstract

Oceanic Isopycnal Slope Spectra. Part II: Turbulence

Cited by 68 publications

References 54 publications

Seismic imaging of a thermohaline staircase in the western tropical North Atlantic

Seismic imaging of a thermohaline staircase in the western tropical North Atlantic

An analytical theory of the buoyancy–Kolmogorov subrange transition in turbulent flows with stable stratification

Concept Tests for a New Wire Flying Vehicle Designed to Achieve High Horizontal Resolution Profiling in Deep Water

Contact Info

Product

Resources

About