A Global Ocean Model with Double-Diffusive Mixing

Merryfield, William J.; Holloway, Greg; Gargett, Ann E.

doi:10.1175/1520-0485(1999)029<1124:agomwd>2.0.co;2

Cited by 78 publications

(50 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ocean dynamics and physics is solved using a time step of 1 h. Vertical physics relies on the parameterization chosen for the CNRM-CM5.1 climate model. The mixed-layer dynamics is parameterized using a double diffusion process (Merryfield et al, 1999), Langmuir cell (Axell, 2002) and account for the contribution of surface wave breaking (Mellor and Blumberg, 2004). A parameterization of bottom intensified tidal-driven mixing similar to Simmons et al (2004) is used in combination with a specific tidal mixing parameterization in the Indonesian area (Koch-Larrouy et al, 2010, 2007.…”

Section: The Physical Corementioning

confidence: 99%

Development and evaluation of CNRM Earth system model – CNRM-ESM1

et al. 2016

View full text Add to dashboard Cite

Abstract.We document the first version of the Centre National de Recherches Météorologiques Earth system model (CNRM-ESM1). This model is based on the physical core of the CNRM climate model version 5 (CNRM-CM5) model and employs the Interactions between Soil, Biosphere and Atmosphere (ISBA) and the Pelagic Interaction Scheme for Carbon and Ecosystem Studies (PISCES) as terrestrial and oceanic components of the global carbon cycle. We describe a preindustrial and 20th century climate simulation following the CMIP5 protocol. We detail how the various carbon reservoirs were initialized and analyze the behavior of the carbon cycle and its prominent physical drivers. Over the 1986-2005 period, CNRM-ESM1 reproduces satisfactorily several aspects of the modern carbon cycle. On land, the model captures the carbon cycling through vegetation and soil, resulting in a net terrestrial carbon sink of 2.2 Pg C year −1 . In the ocean, the large-scale distribution of hydrodynamical and biogeochemical tracers agrees with a modern climatology from the World Ocean Atlas. The combination of biological and physical processes induces a net CO 2 uptake of 1.7 Pg C year −1 that falls within the range of recent estimates. Our analysis shows that the atmospheric climate of CNRM-ESM1 compares well with that of CNRM-CM5. Biases in precipitation and shortwave radiation over the tropics generate errors in gross primary productivity and ecosystem respiration. Compared to CNRM-CM5, the revised oceansea ice coupling has modified the sea-ice cover and ocean ventilation, unrealistically strengthening the flow of North Atlantic deep water (26.1 ± 2 Sv). It results in an accumulation of anthropogenic carbon in the deep ocean.

show abstract

Section: The Physical Corementioning

confidence: 99%

Development and evaluation of CNRM Earth system model – CNRM-ESM1

et al. 2016

View full text Add to dashboard Cite

show abstract

“…NEMOv3.2 uses a partial-step formulation (Barnier et al 2006), which improves the representation of bottom bathymetry and thus water flow and effects of friction at the bottom of the ocean. Compared to the parametrizations of the mixed-layer dynamics used in OPA8, those used in NEMOv3.2 accounts accounts for a double diffusion process (Merryfield et al 1999), Langmuir cell (Axell 2002), and the contribution of surface wave breaking (Mellor and Blumberg 2004;Burchard and Rennau 2008). It also includes a parameterization of bottom intensified tidal-driven mixing, similar to Simmons et al (2004), in combination with a specific tidal mixing parameterization in the Indonesian area (Koch-Larrouy et al 2007, 2010.…”

Section: Ipsl-cm5a-lrmentioning

confidence: 99%

Skill assessment of three earth system models with common marine biogeochemistry

et al. 2012

View full text Add to dashboard Cite

We have assessed the ability of a common ocean biogeochemical model, PISCES, to match relevant modern data fields across a range of ocean circulation fields from three distinct Earth system models: IPSL-CM4-LOOP, IPSL-CM5A-LR and CNRM-CM5.1. The first of these Earth system models has contributed to the IPCC 4th assessment report, while the latter two are contributing to the ongoing IPCC 5th assessment report. These models differ with respect to their atmospheric component, ocean subgrid-scale physics and resolution. The simulated vertical distribution of biogeochemical tracers suffer from biases in ocean circulation and a poor representation of the sinking fluxes of matter. Nevertheless, differences between upper and deep ocean model skills significantly point to changes in the underlying model representations of ocean circulation. IPSL-CM5A-LR and CNRM-CM5.1 poorly represent deep-ocean circulation compared to IPSL-CM4-LOOP degrading the vertical distribution of biogeochemical tracers. However, their representations of surface wind, wind stress, mixed-layer depth and geostrophic circulations (e.g., Antarctic Circumpolar Current) have been improved compared to IPSL-CM4-LOOP. These improvements result in a better representation of large-scale structure of biogeochemical fields in the upper ocean. In particular, a deepening of 20-40 m of the summer mixed-layer depth allows to capture the 0-0.5 lgChl L -1 concentrations class of surface chlorophyll in the Southern Ocean. Further improvements in the representation of the ocean mixedlayer and deep-ocean ventilation are needed for the next generations of models development to better simulate marine biogeochemistry. In order to better constrain ocean dynamics, we suggest that biogeochemical or passive tracer modules should be used routinely for both model development and model intercomparisons.

show abstract

“…Literature on the subject contains at least half a dozen different hypotheses, as reviewed most recently by Radko (2013). For instance, Merryfield (2000) suggested that staircases represent the ultimate state of thermohaline interleaving, which is, in turn, induced by lateral temperature and salinity gradients. Radko (2003) on the other hand argued that doublediffusive layering is likely to be caused by the so-called gamma instability, which is driven by variations in the ratio of the turbulent heat and salt fluxes:…”

Section: Introductionmentioning

confidence: 99%

Double-Diffusive Recipes. Part I: Large-Scale Dynamics of Thermohaline Staircases

Radko

Bulters

Flanagan

et al. 2014

Journal of Physical Oceanography

View full text Add to dashboard Cite

Three-dimensional dynamics of thermohaline staircases are investigated using a series of basin-scale staircase-resolving numerical simulations. The computational domain and forcing fields are chosen to reflect the size and structure of the North Atlantic subtropical thermocline. Salt-finger transport is parameterized using the flux-gradient formulation based on a suite of recent direct numerical simulations. Analysis of the spontaneous generation of thermohaline staircases suggests that thermohaline layering is a product of the gamma instability, associated with the variation of the flux ratio g with the density ratio R r . After their formation, numerical staircases undergo a series of merging events, which systematically increase the size of layers. Ultimately, the system evolves into a steady equilibrium state with pronounced layers 20-50 m thick. The size of the region occupied by thermohaline staircases is controlled by the competition between turbulent mixing and double diffusion. Assuming, in accordance with observations, that staircases form when the density ratio is less than the critical value of R cr ' 1:7, the authors arrive at an indirect estimate of the characteristic turbulent diffusivity in the subtropical thermocline.

show abstract

A Global Ocean Model with Double-Diffusive Mixing

Cited by 78 publications

References 25 publications

Development and evaluation of CNRM Earth system model – CNRM-ESM1

Development and evaluation of CNRM Earth system model – CNRM-ESM1

Skill assessment of three earth system models with common marine biogeochemistry

Double-Diffusive Recipes. Part I: Large-Scale Dynamics of Thermohaline Staircases

Contact Info

Product

Resources

About