Estimating tidally driven mixing in the deep ocean

Laurent, Louis C. St.; Simmons, Harper L.; Jayne, Steven R.

doi:10.1029/2002gl015633

Cited by 312 publications

(333 citation statements)

References 20 publications

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“…Concentrating intense mixing above rough topography where major tidal energy dissipates was found to be preferable for representing deep ocean stratification and Southern Ocean heat uptake in climate models (Saenko, 2006;Exarchou et al, 2013). The model sensitivity study by Jayne (2009) shows that using the tidal mixing parametrization proposed by St Laurent et al (2002) can significantly enhance the deep cell of the meridional overturning circulation (MOC) in comparison with only using an ad hoc background vertical diffusivity, although the upper cell of the MOC and the poleward heat transport (the often used diagnostics for adjudging climate models) are not strongly affected by this parametrization. Present climate and earth system models tend to use the St Laurent et al (2002) parametrization instead of the Bryan and Lewis (1979) type of background diffusivity (e.g.…”

Section: Diapycnal Mixing Associated With Internal Wave Energy Dissipmentioning

confidence: 99%

“…Improved understanding of mixing processes in the ocean has led to a parametrization of abyssal mixing induced by internal wave breaking associated with baroclinic tidal energy (St Laurent et al, 2002;Simmons et al, 2004). Concentrating intense mixing above rough topography where major tidal energy dissipates was found to be preferable for representing deep ocean stratification and Southern Ocean heat uptake in climate models (Saenko, 2006;Exarchou et al, 2013).…”

Section: Diapycnal Mixing Associated With Internal Wave Energy Dissipmentioning

confidence: 99%

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The Finite Element Sea Ice-Ocean Model (FESOM) v.1.4: formulation of an ocean general circulation model

et al. 2014

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Abstract. The Finite Element Sea Ice-Ocean Model (FE-SOM) is the first global ocean general circulation model based on unstructured-mesh methods that has been developed for the purpose of climate research. The advantage of unstructured-mesh models is their flexible multi-resolution modelling functionality. In this study, an overview of the main features of FESOM will be given; based on sensitivity experiments a number of specific parameter choices will be explained; and directions of future developments will be outlined. It is argued that FESOM is sufficiently mature to explore the benefits of multi-resolution climate modelling and that its applications will provide information useful for the advancement of climate modelling on unstructured meshes.

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Section: Diapycnal Mixing Associated With Internal Wave Energy Dissipmentioning

confidence: 99%

Section: Diapycnal Mixing Associated With Internal Wave Energy Dissipmentioning

confidence: 99%

The Finite Element Sea Ice-Ocean Model (FESOM) v.1.4: formulation of an ocean general circulation model

et al. 2014

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“…In these areas, turbulent mixing has been inferred to be 100-1000 times larger than that of the ocean interior. Laurent et al [42] estimated the tidal mixing magnitude around steep bottom is nearly O(10 3 m 2 s 1 ). Tian et al [43] showed that diapycnal diffusivity in the SCS and the Luzon Strait is elevated by two orders of magnitude over that of the smooth bathymetry in the North Pacific, which has a typical background value of an open ocean.…”

Section: The Effects Of Vertical Mixing On Mocmentioning

confidence: 99%

Analysis of deep-layer and bottom circulations in the South China Sea based on eight quasi-global ocean model outputs

et al. 2013

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This study is a preliminary analysis of the South China Sea (SCS) deep circulations using eight quasi-global high-resolution ocean model outputs. The goal is to assess models' ability to simulate these deep circulations. The analysis reveals that models' deep temperatures are colder than the observations in the World Ocean Atlas, while most models' deep salinity values are higher than the observations, indicating models' deep water is generally colder and saltier than the reality. Moreover, there are long-term trends in both temperature and salinity simulations. The Luzon Strait transport below 1500 m is 0.36 Sv when averaged for all models, smaller compared with the observation, which is about 2.5 Sv. Four assimilated models and one unassimilated (OCCAM) display that the Luzon deep-layer overflow reaches its minimum in spring and its maximum in winter. The vertically integrated streamfunctions below 2400 m from these models show a deep cyclonic circulation in the SCS on a large scale, but the pattern is different from the diagnostic streamfunction from the U.S Navy Generalized Digital Environment Model (GDEM-Version 3.0, GDEMv3). The meridional overturning structure above 1000 m is similar in all models, but the spatial distribution and intensity below 1500 m are quite different from model to model. Moreover, the meridional overturning below 2400 m in these models is weaker than that of the GDEMv3, which indicates a deep vertical mixing process in these models is biased weak. Based on the above evaluation, this paper discusses the impacts of T/S initial value, topography, and mixing scheme on the SCS deep circulations, which may provide a reference for future model improvement. quasi-global ocean model, deep-layer and bottom SCS circulations, model evaluation Citation:Xie Q, Xiao J G, Wang D X, et al. Analysis of deep-layer and bottom circulations in the South China Sea based on eight quasi-global ocean model outputs.

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“…TPX08 at 1/30 • (Egbert and Erofeeva, 2002). The parameterisations should include benthic and under-ice mixing (Luneva et al, 2015), and mixing by baroclinic tides (St. Laurent et al, 2002). Simmons et al (2004) consider the application of an internal tide energy flux parameterisation, driven by a barotropic tidal model (St. Laurent et al, 2002;Jayne and St. Laurent, 2001), and how to translate this to an interior vertical diffusivity for implementation in a coarse-resolution ocean circulation model.…”

Section: Tidesmentioning

confidence: 99%

“…The parameterisations should include benthic and under-ice mixing (Luneva et al, 2015), and mixing by baroclinic tides (St. Laurent et al, 2002). Simmons et al (2004) consider the application of an internal tide energy flux parameterisation, driven by a barotropic tidal model (St. Laurent et al, 2002;Jayne and St. Laurent, 2001), and how to translate this to an interior vertical diffusivity for implementation in a coarse-resolution ocean circulation model. In contrast, Allen et al (2010) explore using a 1-D mixing model (GOTM) driven at each horizontal grid cell by imposed sea-surface slopes to estimate the vertical profiles of tidal shear.…”

Section: Tidesmentioning

confidence: 99%

Prospects for improving the representation of coastal and shelf seas in global ocean models

et al. 2017

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Abstract. Accurately representing coastal and shelf seas in global ocean models represents one of the grand challenges of Earth system science. They are regions of immense societal importance through the goods and services they provide, hazards they pose and their role in global-scale processes and cycles, e.g. carbon fluxes and dense water formation. However, they are poorly represented in the current generation of global ocean models. In this contribution, we aim to briefly characterise the problem, and then to identify the important physical processes, and their scales, needed to address this issue in the context of the options available to resolve these scales globally and the evolving computational landscape.We find barotropic and topographic scales are well resolved by the current state-of-the-art model resolutions, e.g. nominal 1/12 • , and still reasonably well resolved at 1/4 • ; here, the focus is on process representation. We identify tides, vertical coordinates, river inflows and mixing schemes as four areas where modelling approaches can readily be transferred from regional to global modelling with substantial benefit. In terms of finer-scale processes, we find that a 1/12 • global model resolves the first baroclinic Rossby radius for only ∼ 8 % of regions < 500 m deep, but this increases to ∼ 70 % for a 1/72 • model, so resolving scales globally requires substantially finer resolution than the current state of the art.We quantify the benefit of improved resolution and process representation using 1/12 • global-and basin-scale northern North Atlantic nucleus for a European model of the ocean (NEMO) simulations; the latter includes tides and a k-ε vertical mixing scheme. These are compared with global stratification observations and 19 models from CMIP5. In terms of correlation and basin-wide rms error, the high-resolution models outperform all these CMIP5 models. The model with tides shows improved seasonal cycles compared to the highresolution model without tides. The benefits of resolution are particularly apparent in eastern boundary upwelling zones.To explore the balance between the size of a globally refined model and that of multiscale modelling options (e.g. finite element, finite volume or a two-way nesting approach), we consider a simple scale analysis and a conceptual grid refining approach. We put this analysis in the context of evolving computer systems, discussing model turnaround time, scalability and resource costs. Using a simple cost model compared to a reference configuration (taken to be a 1/4 • global model in 2011) and the increasing performance of the UK Research Councils' computer facility, we estimate an unstructured mesh multiscale approach, resolving process scales down to 1.5 km, would use a comparable share of the computer resource by 2021, the two-way nested multiscale approach by 2022, and a 1/72 • global model by 2026. However, we also note that a 1/12 • global model would not have a comparable computational cost to a 1 • global model in 2017 until 2027. Hence, we conc...

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Estimating tidally driven mixing in the deep ocean

Cited by 312 publications

References 20 publications

The Finite Element Sea Ice-Ocean Model (FESOM) v.1.4: formulation of an ocean general circulation model

The Finite Element Sea Ice-Ocean Model (FESOM) v.1.4: formulation of an ocean general circulation model

Analysis of deep-layer and bottom circulations in the South China Sea based on eight quasi-global ocean model outputs

Prospects for improving the representation of coastal and shelf seas in global ocean models

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