Long-Term Simulations of Upper Ocean Vertical Mixing Using Models of Different Types

Gaspar, Philippe; Gregoris, Y.; Stull, Roland B.; Boissier, C.

doi:10.1016/s0422-9894(08)70545-2

Cited by 9 publications

(5 citation statements)

References 11 publications

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“…nocline is inherent in the parameterization and would be due to decreasing buoyancy [e.g., Mourn and Osborn, 1986]. The use of such eddy diffusivity parameterization is still under discussion (see Gaspar et al [1988] or Cummins et al [1990]), but similar vertical distributions of K(z) were successfully used to simulate the vertical distribution of phytoplankton biomass, nutrients, and dissolved oxygen for the same area or in similar ecological situations in previous studies [Zakardfian and Varela et al, 1992Varela et al, , 1994]. In particular, the depth value of [Kiefer and Mitchell, 1983] [Williams et al, 1979] molar ratio for oxygen consumption during ammonia oxidation [Kaplan, 1983] molar ratio for oxygen consumption during nitrite oxidation [Kaplan, 1983] molar ratio for oxygen consumption during ammonia excretion by zooplankton 3 piston velocity of the O2 atmosphere/ocean exchange function thickness of the imposed upper mixed layer horizontal length scale of the upward motions zone time step of the Eulerian grid spatial increment of the Eulerian grid (Sz = H = 10 m for the single upper mixed layer grid point) Here var denotes variables by opposition to parameters.…”

Section: Physical Processesmentioning

confidence: 99%

Biological and chemical signs of upward motions in permanent geostrophic fronts of the western Mediterranean

Zakardjian¹,

Prieur²

1998

J. Geophys. Res.

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Abstract. Upward motions are often invoked to explain the high productivity of permanent geostrophic fronts in the Western Mediterranean while physical evidence of such upward advections is seldom reported. The goal of this study is to define biological and chemical criteria, which can be used to localize such upward motions zones. We use a one-dimensional, time-dependent model of phytoplankton dynamics to test the effects of upward advection on the vertical distribution of phytoplankton biomass, nutrients, and dissolved oxygen.

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Section: Physical Processesmentioning

confidence: 99%

Biological and chemical signs of upward motions in permanent geostrophic fronts of the western Mediterranean

Zakardjian¹,

Prieur²

1998

J. Geophys. Res.

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“…Accordingly, they are often referred to as kinetic energy (KE) models. Without being as fast as the simplest integral models or as detailed as the high-order closure schemes, they provide realistic simulations of the vertical turbulent mixing with a reasonable computational efficiency [Martin, 1986;Gaspar et al, 1988]. In addition, scales, from the inertial period to a few days.…”

Section: Introductionmentioning

confidence: 99%

A simple eddy kinetic energy model for simulations of the oceanic vertical mixing: Tests at station Papa and long‐term upper ocean study site

Gaspar¹,

Gregoris²,

Lefèvre³

1990

J. Geophys. Res.

715

615

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A simple eddy kinetic energy parameterization of the oceanic vertical mixing is presented. The parameterization scheme is based on recent works on atmospheric turbulence modeling. It is designed to simulate vertical mixing at all depths, from the upper boundary layer down to the abyss. This scheme includes a single prognostic equation for the turbulent kinetic energy. The computation of the turbulent length scales is diagnostic, rather than prognostic. In weakly turbulent regions the simulated vertical diffusivity is inversely proportional to the Brunt-Vai'sala frequency. In the first validation experiments presented here, the vertical mixing scheme is embedded into a simple one-dimensional model and used for upper ocean simulations at two very different test sites: the station Papa in the Gulf of Alaska and the Long-Term Upper Ocean Study (LOTUS) mooring in the Sargasso Sea. At station Papa the model successfully simulates the seasonal evolution of the upper ocean temperature field. At LOTUS the focus is on a short 2-week period. A detailed analysis of the oceanic heat budget during that period reveals a large bias in the bulk-derived surface heat fluxes. After correction of the fluxes the model does well in simulating the evolution of the temperature and wind-driven current. In particular, the large observed diurnal cycles of the sea surface temperature are well reproduced. During the second (windy) week of the selected period the model accounts for about two thirds of the kinetic energy of the observed upper ocean currents at periods larger than 6 hours. The local wind forcing thus appears to be the dominant generation mechanism for the near-inertial motions, which are the most energetic. The velocity simulation is especially good at the low frequencies. During the second simulated week the model accounts for as much as 78% of the kinetic energy at subinertial frequencies. The simulated mean velocity profile is reminiscent of an Ekman spiral, in agreement with the observations. 1. 16,179 16,180 GASPAR ET AL.' A SIMPLE EDDY KINETIC ENERGY MODEL FOR VERTICAL MIXING nearly optimal assimilation techniques can be associated with their discretized form [Mort et al., 1988]. Such models thus meet our basic requirements. However, they have a main weak point in the determination of a turbulent master length scale [Mellor and Yamada, 1982]. The master length can be either specified as a function of different characteristic turbulent scales or computed from a prognostic equation. In most oceanic applications [e.g., Mellor and Durbin, 1975; Klein and Coantic, 1981; Martin, 1985; AndrO and Lacar-r&re, 1985], that length is specified and specially tailored for ML modeling. It is generally dependent on the Blackadar [1962] length scale which is meaningless when several isolated turbulent regions are present in the water column. This again limits the use of such schemes in boundary layer modeling as is the case for the bulk models. On the contrary, the prognostic equation for the master length [Mellor and Yamada, 1974] is gene...

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“…The underlying theories of these two model classes have been discussed and critiqued by many authors [e.g., Woods, 1977;Niiler and Kraus, 1977;Harleman, 1982;Kraus, 1988;Hearn, 1988;McCormick and Meadows, 1988;Henderson-Sellers and Davies, 1989]. Intermodel comparisons have been made to illustrate the strengths and weaknesses in the performance of different mixed-layer and eddy diffusion models [e.g., Martin, 1985;Gaspar et al, 1988;McCormick and Meadows, 1988].…”

Section: Introductionmentioning

confidence: 99%

“…To meet this objective, an eddy diffusion model was selected. Models of this class have been used successfully to simulate thermal stratification in a variety of limnologic studies [e.g., Babajimopoulos and Papadopoulos, 1986;Kirk, 1988;Aldama et al, 1989] and have been shown to predict adequately both surface temperature and the seasonal storage of heat [e.g., Martin, 1985;Gaspar et al, 1988;McCormick and Meadows, 1988]. In addition to their predictive capabilities, eddy diffusion models are numerically stable over long periods of integration, during which propagation of errors seriously could affect model results.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of lake evaporation with application to modeling lake-level variations at Harney-Malheur Lake, Oregon

Hostetler¹

1990

Water Resour. Res.

101

173

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A physically based eddy diffusion model for simulating the seasonal variation in lake temperature and evaporation is presented and validated. Because no lake-specific fitting of the parameters of the model is necessary, the model can be used to simulate evaporation in studies of climate change and lake hydrology in a variety of settings. The eddy diffusion model is used to simulate evaporation for input to a simple lake level model that is applied to reconstruct recent fluctuations in the level of Harney-Malheur Lake caused by climatic variations.

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Long-Term Simulations of Upper Ocean Vertical Mixing Using Models of Different Types

Cited by 9 publications

References 11 publications

Biological and chemical signs of upward motions in permanent geostrophic fronts of the western Mediterranean

Biological and chemical signs of upward motions in permanent geostrophic fronts of the western Mediterranean

A simple eddy kinetic energy model for simulations of the oceanic vertical mixing: Tests at station Papa and long‐term upper ocean study site

Simulation of lake evaporation with application to modeling lake-level variations at Harney-Malheur Lake, Oregon

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