A comparison of Langmuir turbulence parameterizations and key wave effects in a numerical model of the North Atlantic and Arctic Oceans

Ali, Alfatih; Christensen, Kai Håkon; Breivik, Øyvind; Malila, Mika; Raj, Roshin P.; Bertino, Laurent; Chassignet, Eric P.; Bakhoday-Paskyabi, Mostafa

doi:10.1016/j.ocemod.2019.02.005

Cited by 20 publications

(13 citation statements)

References 71 publications

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“…This allowed to highlight the significant improvement in to deepen the mixed layer and therefore have a cumulative effect. However the main contributor is the modified Langmuir cell parameterization of Axell (2002) which is consistent with recent results obtained by Reichl et al (2016) and Ali et al (2019) using a KPP closure scheme.…”

supporting

confidence: 88%

Development of a 2-way coupled ocean-wave model: assessment on a global NEMO(v3.6)-WW3(v6.02) coupled configuration

Couvelard¹,

Lemarié²,

Samson³

et al. 2019

Preprint

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Abstract. This paper describes the implementation of a coupling between a three-dimensional ocean general circulation model (NEMO) and a wave model (WW3) to represent the interactions of the upper oceanic flow dynamics with surface waves. The focus is on the impact of such coupling on upper-ocean properties (temperature and currents) and mixed-layer depths (MLD) at global eddying scales. A generic coupling interface has been developed and the NEMO governing equations and boundary conditions have been adapted to include wave-induced terms following the approach of McWilliams et al. (2004) and Ardhuin et al. (2008). In particular, the contributions of Stokes-Coriolis, Vortex and surface pressure forces have been implemented on top of the necessary modifications of the tracer/continuity equation and turbulent closure scheme (a 1-equation TKE closure here). To assess the new developments, we perform a set of sensitivity experiments with a global oceanic configuration at 1/4° resolution coupled with a wave model configured at 1/2° resolution. Numerical simulations show a global increase of wind-stress due to the interaction with waves (via the Charnock coefficient) particularly at high latitudes. The modifications brought to the TKE closure scheme and the inclusion of a parameterization for Langmuir turbulence lead to a significant increase of the mixing thus helping to deepen the MLD. This deepening is mainly located in the Southern Hemisphere and results in reduced sea-surface currents and temperatures.

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supporting

confidence: 88%

Development of a 2-way coupled ocean-wave model: assessment on a global NEMO(v3.6)-WW3(v6.02) coupled configuration

Couvelard¹,

Lemarié²,

Samson³

et al. 2019

Preprint

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“…A typical approach for examining OSBL schemes compares different schemes in a common OGCM (e.g., Ali et al, ; Fan & Griffies, ; Large et al, ; Li et al, ; Li & Fox‐Kemper, ), often seeking to reduce model bias versus observations. However, this approach has results that are influenced strongly by other biases in the OGCM.…”

Section: Introductionmentioning

confidence: 99%

Comparing Ocean Surface Boundary Vertical Mixing Schemes Including Langmuir Turbulence

Reichl

Fox‐Kemper

et al. 2019

J Adv Model Earth Syst

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Six recent Langmuir turbulence parameterization schemes and five traditional schemes are implemented in a common single-column modeling framework and consistently compared. These schemes are tested in scenarios versus matched large eddy simulations, across the globe with realistic forcing (JRA55-do, WAVEWATCH-III simulated waves) and initial conditions (Argo), and under realistic conditions as observed at ocean moorings. Traditional non-Langmuir schemes systematically underpredict large eddy simulation vertical mixing under weak convective forcing, while Langmuir schemes vary in accuracy. Under global, realistic forcing Langmuir schemes produce 6% (−1% to 14% for 90% confidence) or 5.2 m (−0.2 m to 17.4 m for 90% confidence) deeper monthly mean mixed layer depths than their non-Langmuir counterparts, with the greatest differences in extratropical regions, especially the Southern Ocean in austral summer. Discrepancies among Langmuir schemes are large (15% in mixed layer depth standard deviation over the mean): largest under wave-driven turbulence with stabilizing buoyancy forcing, next largest under strongly wave-driven conditions with weak buoyancy forcing, and agreeing during strong convective forcing. Non-Langmuir schemes disagree with each other to a lesser extent, with a similar ordering. Langmuir discrepancies obscure a cross-scheme estimate of the Langmuir effect magnitude under realistic forcing, highlighting limited understanding and numerical deficiencies. Maps of the regions and seasons where the greatest discrepancies occur are provided to guide further studies and observations.

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“…Several ocean and wave model studies (Ali et al, ; Belcher et al, ; Breivik et al, ; Li et al, ) and fully coupled atmosphere‐wave‐ocean climate models (Breivik et al, ; Fan & Griffies, ; Li et al, ) have investigated the relationship between Langmuir turbulence and upper ocean mixing and how this may change under a changing climate. It is clear that Langmuir turbulence will enhance the vertical extent of the air‐sea gas exchange brought about by wave breaking and thus affect the vertical distribution of buoyant particles.…”

Section: Introductionmentioning

confidence: 99%

Long‐Term Statistics of Observed Bubble Depth Versus Modeled Wave Dissipation

et al. 2020

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Air bubble penetration depths are investigated with a bottom‐mounted echosounder at a seabed observatory in northern Norway. We compare a 1‐year time series of observed bubble depth against modeled and estimated turbulent kinetic energy flux from breaking waves as well as wind speed and sea state. We find that the hourly mean and maximum bubble depths are highly variable, reaching 18 and 38 m, respectively, and strongly correlated with wind and sea state. The bubble depth is shallowest during summer following the seasonal variations in wind speed and wave height. Summertime shallowing of the mixed layer depth is not limiting the penetration depth. A strong relationship between bubble depth and modeled turbulent kinetic energy flux from breaking waves is found, similar in strength to the relationship between bubble depth and wind speed. The wind sea is more strongly correlated with bubble depth than the total significant wave height, and the swell is only weakly correlated, suggesting that the wave model does a reasonable separation of swell and wind sea.

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A comparison of Langmuir turbulence parameterizations and key wave effects in a numerical model of the North Atlantic and Arctic Oceans

Cited by 20 publications

References 71 publications

Development of a 2-way coupled ocean-wave model: assessment on a global NEMO(v3.6)-WW3(v6.02) coupled configuration

Development of a 2-way coupled ocean-wave model: assessment on a global NEMO(v3.6)-WW3(v6.02) coupled configuration

Comparing Ocean Surface Boundary Vertical Mixing Schemes Including Langmuir Turbulence

Long‐Term Statistics of Observed Bubble Depth Versus Modeled Wave Dissipation

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