Nonlocal fluxes and Stokes drift effects in the K-profile parameterization

Smyth, William D.; Skyllingstad, Eric D.; Crawford, Greg; Wijesekera, H. W.

doi:10.1007/s10236-002-0012-9

Cited by 100 publications

(102 citation statements)

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“…Many velocity scales have been introduced to characterize Langmuir turbulence based on observations, theory, and numerical models (Harcourt and D'Asaro 2008;Grant and Belcher 2009;McWilliams and Sullivan 2000;Plueddemann et al 1996;Smith 1996Smith , 1998Smyth et al 2002). Building on these previous ideas, we will introduce a turbulent velocity scale U that is applicable to a wide range of wind and wave conditions in which turbulence can be predominantly driven by waves, Eulerian shear flow, or both processes.…”

Section: ) Scaling Tke Budgetsmentioning

confidence: 99%

Rapid Mixed Layer Deepening by the Combination of Langmuir and Shear Instabilities: A Case Study

Kukulka

Plueddemann

Trowbridge

et al. 2010

Journal of Physical Oceanography

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Langmuir circulation (LC) is a turbulent upper-ocean process driven by wind and surface waves that contributes significantly to the transport of momentum, heat, and mass in the oceanic surface layer. The authors have previously performed a direct comparison of large-eddy simulations and observations of the upper-ocean response to a wind event with rapid mixed layer deepening. The evolution of simulated crosswind velocity variance and spatial scales, as well as mixed layer deepening, was only consistent with observations if LC effects are included in the model. Based on an analysis of these validated simulations, in this study the fundamental differences in mixing between purely shear-driven turbulence and turbulence with LC are identified. In the former case, turbulent kinetic energy (TKE) production due to shear instabilities is largest near the surface, gradually decreasing to zero near the base of the mixed layer. This stands in contrast to the LC case in which at middepth range TKE production can be dominated by Stokes drift shear. Furthermore, the Eulerian mean vertical shear peaks near the base of the mixed layer so that TKE production by mean shear flow is elevated there. LC transports horizontal momentum efficiently downward leading to an along-wind velocity jet below LC downwelling regions at the base of the mixed layer. Locally enhanced vertical shear instabilities as a result of this jet efficiently erode the thermocline. In turn, enhanced breaking internal waves inject cold deep water into the mixed layer, where LC currents transport temperature perturbation advectively. Thus, LC and locally generated shear instabilities work intimately together to facilitate strongly the mixed layer deepening process.

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Section: ) Scaling Tke Budgetsmentioning

confidence: 99%

Rapid Mixed Layer Deepening by the Combination of Langmuir and Shear Instabilities: A Case Study

Kukulka

Plueddemann

Trowbridge

et al. 2010

Journal of Physical Oceanography

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“…In the KPP scheme the diffusivity profile is specified through a similarity profile, using the velocity and length scales appropriate to the turbulent flow. Modifications to the KPP scheme to take account of Langmuir turbulence have been proposed (McWilliams and Sullivan 2000;Smyth et al 2002) assuming that the velocity scale is ;u s0 (Smith 1998). However, without an understanding of the scaling of Langmuir turbulence, the accuracy of the proposed parameterizations remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Langmuir Turbulence in the Ocean Mixed Layer

Grant

Belcher

2009

Journal of Physical Oceanography

141

198

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This study uses large-eddy simulation (LES) to investigate the characteristics of Langmuir turbulence through the turbulent kinetic energy (TKE) budget. Based on an analysis of the TKE budget a velocity scale for Langmuir turbulence is proposed. The velocity scale depends on both the friction velocity and the surface Stokes drift associated with the wave field. The scaling leads to unique profiles of nondimensional dissipation rate and velocity component variances when the Stokes drift of the wave field is sufficiently large compared to the surface friction velocity. The existence of such a scaling shows that Langmuir turbulence can be considered as a turbulence regime in its own right, rather than a modification of shear-driven turbulence.Comparisons are made between the LES results and observations, but the lack of information concerning the wave field means these are mainly restricted to comparing profile shapes. The shapes of the LES profiles are consistent with observed profiles. The dissipation length scale for Langmuir turbulence is found to be similar to the dissipation length scale in the shear-driven boundary layer. Beyond this it is not possible to test the proposed scaling directly using available data. Entrainment at the base of the mixed layer is shown to be significantly enhanced over that due to normal shear turbulence.

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Section: Discussionmentioning

confidence: 99%

“…However, the impact of waves on OBL dynamics is acknowledged in more recent bulk models (e.g. Craig & Banner 1994;Smyth et al 2002;Kantha & Clayson 2004;Melsom & SAEtra 2004;Ardhuin & Jenkins 2006;Rascale, Ardhuin & Terray 2006), with improvements motivated by better measurements and results from turbulence-resolving simulations with wave effects as described here.…”

Section: Introductionmentioning

confidence: 99%

“…This needs to be checked with new instrumentation and focused field campaigns and additional explorations of the LES parameter space. The present LES results are an impetus to incorporate more fully wave influences in bulk models of the OBL such as the K-profile parameterization (Large et al 1995;Smyth et al 2002;McWilliams & Huckle 2006).Perhaps the greatest need is to improve the description of the breaking statistics as a function of wind speed, wave age and wind-wave misalignment. The statistical description of breaking used here is speculative, and may be criticized for its incompleteness, but we believe that the significance of the new dynamics that is introduced to OBL modeling by the explicit inclusion of both breaking and Langmuir turbulence justifies the sometimes crude assumptions made here.…”

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confidence: 99%

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Impacts of Ocean Waves on the Atmospheric Surface Layer: Simulations and Observations

Sullivan¹,

McWilliams²

2007

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Standard Form 298 (Rev. 8/98) REPORT DOCUMENTATION PAGEPrescribed by ANSI Std. Z39.18 Form Approved OMB No. 0704-0188The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY)2. REPORT TYPE 3. DATES COVERED (From -To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER This this award investigated surface boundary layers and air-sea interaction with theoretical and numerical research. Our long term scientific objective was to explore the nature of intermittency, coherent structures, and turbulent fluxes and their coupling in the surface layers of the marine atmospheric and oceanic planetary boundary layers (PBL). Efforts were focused on the effects of surface gravity waves on the near-surface dynamics, surface fluxes, and coupling between the atmospheric and oceanic PBLs. The final results of this work are provided in 2 journal articles and a reviewed meeting paper. AUTHOR(S) PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S)12Peter Sullivan Abstract. Gravity waves on the sea surface reflect coupling between the atmosphere and ocean. They play important dynamical roles in the transfer of momentum, heat, and scalars, but how they interact with background oceanic (and atmospheric) turbulence is still not well understood. This is especially true under high winds where waves foster Langmuir circulations but also break intermittently.Results from high-resolution large eddy simulations (LESs) that include stochastic breaking waves and the Craik-Leibovich "vortex force" are analyzed. Under certain sea states turbulence (anisotropic seed vorticity) generated by breaking waves initiates Craik-Leibovich instabilities that lead to coherent structures, viz., Langmuir cells and intermittent downwelling jets both of which impact ocean mixing. We suggest a mechanism as to how breaking waves couple with the vortex force that leads to the formation of these flow structures. IntroductionGravity waves at the sea s...

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Nonlocal fluxes and Stokes drift effects in the K-profile parameterization

Cited by 100 publications

References 29 publications

Rapid Mixed Layer Deepening by the Combination of Langmuir and Shear Instabilities: A Case Study

Rapid Mixed Layer Deepening by the Combination of Langmuir and Shear Instabilities: A Case Study

Characteristics of Langmuir Turbulence in the Ocean Mixed Layer

Impacts of Ocean Waves on the Atmospheric Surface Layer: Simulations and Observations

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