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  • 1
    Online Resource
    Online Resource
    Breaking internal wave groups: Mixing and momentum fluxes
    AIP Publishing ; 2011
    In:  Physics of Fluids Vol. 23, No. 9 ( 2011-09-01)
    Details
    In: Physics of Fluids, AIP Publishing, Vol. 23, No. 9 ( 2011-09-01)
    Abstract: Breaking groups of large-amplitude internal gravity waves are simulated numerically and the resulting diapycnal mixing and residual momentum are quantified. The wave frequency strongly affects the mixing, with high- and low-frequency waves doing many times more mixing than intermediate-frequency waves with the same steepness. The total residual momentum remaining in the breaking region after the remnants of the wave group propagates away shows similar frequency dependence as the diapycnal mixing. Additionally, the propagation of the breaking events and the spatial distribution of the mixing are found to agree qualitatively with a kinematic description of breaking internal wave groups.
    Type of Medium: Online Resource
    ISSN: 1070-6631 , 1089-7666
    URL: Article
    DOI: 10.1063/1.3638155
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2011
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  • 2
    Online Resource
    Online Resource
    Dispersion in the Open Ocean Seasonal Pycnocline at Scales of 1–10 km and 1–6 days
    American Meteorological Society ; 2020
    In:  Journal of Physical Oceanography Vol. 50, No. 2 ( 2020-02), p. 415-437
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 50, No. 2 ( 2020-02), p. 415-437
    Abstract: Results are presented from two dye release experiments conducted in the seasonal thermocline of the Sargasso Sea, one in a region of low horizontal strain rate (~10 −6 s −1 ), the second in a region of intermediate horizontal strain rate (~10 −5 s −1 ). Both experiments lasted ~6 days, covering spatial scales of 1–10 and 1–50 km for the low and intermediate strain rate regimes, respectively. Diapycnal diffusivities estimated from the two experiments were κ z = (2–5) × 10 −6 m 2 s −1 , while isopycnal diffusivities were κ H = (0.2–3) m 2 s −1 , with the range in κ H being less a reflection of site-to-site variability, and more due to uncertainties in the background strain rate acting on the patch combined with uncertain time dependence. The Site I (low strain) experiment exhibited minimal stretching, elongating to approximately 10 km over 6 days while maintaining a width of ~5 km, and with a notable vertical tilt in the meridional direction. By contrast, the Site II (intermediate strain) experiment exhibited significant stretching, elongating to more than 50 km in length and advecting more than 150 km while still maintaining a width of order 3–5 km. Early surveys from both experiments showed patchy distributions indicative of small-scale stirring at scales of order a few hundred meters. Later surveys show relatively smooth, coherent distributions with only occasional patchiness, suggestive of a diffusive rather than stirring process at the scales of the now larger patches. Together the two experiments provide important clues as to the rates and underlying processes driving diapycnal and isopycnal mixing at these scales.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    URL: Article
    DOI: 10.1175/JPO-D-19-0019.1
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2020
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 3
    Online Resource
    Online Resource
    Observations and numerical simulations of large‐eddy circulation in the ocean surface mixed layer
    American Geophysical Union (AGU) ; 2014
    In:  Geophysical Research Letters Vol. 41, No. 21 ( 2014-11-16), p. 7584-7590
    Details
    In: Geophysical Research Letters, American Geophysical Union (AGU), Vol. 41, No. 21 ( 2014-11-16), p. 7584-7590
    Abstract: Ocean dye releases were mapped using scanning, depth‐resolving airborne lidar Dye evolved into rolls aligned with the wind and/or near‐surface current Large‐eddy simulations showed similar features without Stokes drift forcing
    Type of Medium: Online Resource
    ISSN: 0094-8276 , 1944-8007
    URL: Issue
    URL: Article
    DOI: 10.1002/grl.v41.21
    DOI: 10.1002/2014GL061637
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2014
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    SSG: 16,13
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  • 4
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    On the Geostrophic Adjustment of an Isolated Lens: Dependence on Burger Number and Initial Geometry*
    American Meteorological Society ; 2011
    In:  Journal of Physical Oceanography Vol. 41, No. 4 ( 2011-04-01), p. 725-741
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 41, No. 4 ( 2011-04-01), p. 725-741
    Abstract: Geostrophic adjustment of an isolated axisymmetric lens was examined to better understand the dependence of radial displacements and the adjusted velocity on the Burger number and the geometry of initial conditions. The behavior of the adjustment was examined using laboratory experiments and numerical simulations, which were in turn compared to published analytical solutions. Three defining length scales of the initial conditions were used to distinguish between various asymptotic behaviors for large and small Burger numbers: the Rossby radius of deformation, the horizontal length scale of the initial density defect, and the horizontal length scale of the initial pressure gradient. Numerical simulations for the fully nonlinear time-dependent adjustment agreed both qualitatively and quantitatively with analogous analytical solutions. For large Burger numbers, similar agreement was found in laboratory experiments. Results show that a broad range of final states can result from different initial geometries, depending on the values of the relevant length scales and the Burger number computed from initial conditions. For Burger numbers much larger or smaller than unity, differences between different initial geometries can readily exceed an order of magnitude for both displacement and velocity.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    URL: Article
    DOI: 10.1175/2010JPO4476.1
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2011
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  • 5
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    Online Resource
    The LatMix Summer Campaign: Submesoscale Stirring in the Upper Ocean
    American Meteorological Society ; 2015
    In:  Bulletin of the American Meteorological Society Vol. 96, No. 8 ( 2015-08-01), p. 1257-1279
    Details
    In: Bulletin of the American Meteorological Society, American Meteorological Society, Vol. 96, No. 8 ( 2015-08-01), p. 1257-1279
    Abstract: Lateral stirring is a basic oceanographic phenomenon affecting the distribution of physical, chemical, and biological fields. Eddy stirring at scales on the order of 100 km (the mesoscale) is fairly well understood and explicitly represented in modern eddy-resolving numerical models of global ocean circulation. The same cannot be said for smaller-scale stirring processes. Here, the authors describe a major oceanographic field experiment aimed at observing and understanding the processes responsible for stirring at scales of 0.1–10 km. Stirring processes of varying intensity were studied in the Sargasso Sea eddy field approximately 250 km southeast of Cape Hatteras. Lateral variability of water-mass properties, the distribution of microscale turbulence, and the evolution of several patches of inert dye were studied with an array of shipboard, autonomous, and airborne instruments. Observations were made at two sites, characterized by weak and moderate background mesoscale straining, to contrast different regimes of lateral stirring. Analyses to date suggest that, in both cases, the lateral dispersion of natural and deliberately released tracers was O(1) m2 s–1 as found elsewhere, which is faster than might be expected from traditional shear dispersion by persistent mesoscale flow and linear internal waves. These findings point to the possible importance of kilometer-scale stirring by submesoscale eddies and nonlinear internal-wave processes or the need to modify the traditional shear-dispersion paradigm to include higher-order effects. A unique aspect of the Scalable Lateral Mixing and Coherent Turbulence (LatMix) field experiment is the combination of direct measurements of dye dispersion with the concurrent multiscale hydrographic and turbulence observations, enabling evaluation of the underlying mechanisms responsible for the observed dispersion at a new level.
    Type of Medium: Online Resource
    ISSN: 0003-0007 , 1520-0477
    URL: Article
    URL: Article
    DOI: 10.1175/BAMS-D-14-00015.1
    DOI: 10.1175/BAMS-D-14-00015.3
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2015
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    detail.hit.zdb_id: 419957-1
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  • 6
    Online Resource
    Online Resource
    Submesoscale streamers exchange water on the north wall of the Gulf Stream
    American Geophysical Union (AGU) ; 2016
    In:  Geophysical Research Letters Vol. 43, No. 3 ( 2016-02-16), p. 1226-1233
    Details
    In: Geophysical Research Letters, American Geophysical Union (AGU), Vol. 43, No. 3 ( 2016-02-16), p. 1226-1233
    Abstract: Lateral detrainment clearly observed from North Wall at depth Salt flux similar to bulk estimates Detrained water is from a distinct partially mixed water class
    Type of Medium: Online Resource
    ISSN: 0094-8276 , 1944-8007
    URL: Issue
    URL: Article
    DOI: 10.1002/grl.v43.3
    DOI: 10.1002/2015GL067152
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2016
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    detail.hit.zdb_id: 7403-2
    SSG: 16,13
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  • 7
    Online Resource
    Online Resource
    Enhanced mixing across the gyre boundary at the Gulf Stream front
    Proceedings of the National Academy of Sciences ; 2020
    In:  Proceedings of the National Academy of Sciences Vol. 117, No. 30 ( 2020-07-28), p. 17607-17614
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 117, No. 30 ( 2020-07-28), p. 17607-17614
    Abstract: The Gulf Stream front separates the North Atlantic subtropical and subpolar ocean gyres, water masses with distinct physical and biogeochemical properties. Exchange across the front is believed to be necessary to balance the freshwater budget of the subtropical gyre and to support the biological productivity of the region; however, the physical mechanisms responsible have been the subject of long-standing debate. Here, the evolution of a passive dye released within the north wall of the Gulf Stream provides direct observational evidence of enhanced mixing across the Gulf Stream front. Numerical simulations indicate that the observed rapid cross-frontal mixing occurs via shear dispersion, generated by frontal instabilities and episodic vertical mixing. This provides unique direct evidence for the role of submesoscale fronts in generating lateral mixing, a mechanism which has been hypothesized to be of general importance for setting the horizontal structure of the ocean mixed layer. Along the Gulf Stream front in the North Atlantic, these observations further suggest that shear dispersion at sharp fronts may provide a source of freshwater flux large enough to explain much of the freshwater deficit in the subtropical-mode water budget and a flux of nutrients comparable to other mechanisms believed to control primary productivity in the subtropical gyre.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.2005558117
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2020
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    SSG: 11
    SSG: 12
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  • 8
    Online Resource
    Online Resource
    Spatial and temporal variations of Richardson number on Georges Bank
    American Geophysical Union (AGU) ; 2006
    In:  Geophysical Research Letters Vol. 33, No. 6 ( 2006)
    Details
    In: Geophysical Research Letters, American Geophysical Union (AGU), Vol. 33, No. 6 ( 2006)
    Type of Medium: Online Resource
    ISSN: 0094-8276
    URL: Article
    DOI: 10.1029/2005GL024903
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2006
    detail.hit.zdb_id: 2021599-X
    detail.hit.zdb_id: 7403-2
    SSG: 16,13
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  • 9
    Online Resource
    Online Resource
    Lateral dispersion over the continental shelf: Analysis of dye release experiments
    American Geophysical Union (AGU) ; 2001
    In:  Journal of Geophysical Research: Oceans Vol. 106, No. C5 ( 2001-05-15), p. 9603-9621
    Details
    In: Journal of Geophysical Research: Oceans, American Geophysical Union (AGU), Vol. 106, No. C5 ( 2001-05-15), p. 9603-9621
    Abstract: Lateral dispersion over the continental shelf was examined using dye studies performed as a part of the Coastal Mixing and Optics experiment. Four experiments performed at intermediate depths, each lasting 2.5–5 days, were examined. In some cases the dye patches remained fairly homogeneous both vertically and horizontally throughout an experiment. In other cases, significant patchiness was observed on scales ranging from 2 to 10 m vertically and a few hundred meters to a few kilometers horizontally. The observations showed that the dye distributions were significantly influenced by shearing and straining on scales of 5–10 m in the vertical and 1–10 km in the horizontal. Superimposed on these larger‐scale distortions were simultaneous increases in the horizontal second moments of the dye patches, with corresponding horizontal diffusivities based on a Fickian diffusion model of 0.3–4.9 m 2 s −1 . Analysis of the dye data in concert with shear estimates from shipboard acoustic Doppler current profiler observations showed that the existing paradigms of shear dispersion and dispersion by interleaving water masses cannot account for the observed diffusive spreading of the dye patches. This result suggests that some other mechanisms provided an additional diffusivity of order 0.2–4.6 m 2 s −1 . An alternative mechanism, dispersion by vortical motions caused by the relaxation of diapycnal mixing events, may explain the observed dispersion in some cases.
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/2000JC900138
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2001
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    detail.hit.zdb_id: 3094104-0
    detail.hit.zdb_id: 2130824-X
    detail.hit.zdb_id: 2016813-5
    detail.hit.zdb_id: 2016810-X
    detail.hit.zdb_id: 2403298-0
    detail.hit.zdb_id: 2016800-7
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    detail.hit.zdb_id: 161667-5
    detail.hit.zdb_id: 2969341-X
    detail.hit.zdb_id: 161665-1
    detail.hit.zdb_id: 3094268-8
    detail.hit.zdb_id: 710256-2
    detail.hit.zdb_id: 2016804-4
    detail.hit.zdb_id: 3094181-7
    detail.hit.zdb_id: 3094219-6
    detail.hit.zdb_id: 3094167-2
    detail.hit.zdb_id: 2220777-6
    detail.hit.zdb_id: 3094197-0
    SSG: 16,13
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  • 10
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    Online Resource
    Geostrophic Adjustment of an Isolated Diapycnal Mixing Event and Its Implications for Small-Scale Lateral Dispersion
    American Meteorological Society ; 2005
    In:  Journal of Physical Oceanography Vol. 35, No. 12 ( 2005-12-01), p. 2352-2367
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 35, No. 12 ( 2005-12-01), p. 2352-2367
    Abstract: In this first of two companion papers, the time-dependent relaxation of an isolated diapycnal mixing event is examined in detail by means of numerical simulations, with an emphasis on the energy budget, particle displacements, and their implications for submesoscale oceanic lateral dispersion. The adjustment and dispersion characteristics are examined as a function of the lateral extent of the event L relative to the Rossby radius of deformation R. The strongest circulations and horizontal displacements occur in the regime R/L ≈ O(1). For short times, less than an inertial period, horizontal displacements are radial. Once the adjustment is completed, displacements become primarily azimuthal and continue to stir fluid over several to tens of inertial periods. The cumulative effect of many such events in terms of the effective lateral dispersion that they induce is examined in the companion paper.
    Type of Medium: Online Resource
    ISSN: 1520-0485 , 0022-3670
    URL: Article
    DOI: 10.1175/JPO2835.1
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2005
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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