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Showing 1 to 20 of 43 for “"diapycnal"”.
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Diapycnal mixing transience and the meridional overturning circulation
Diapycnal mixing of ocean waters is crucial to the dynamics and associated heat transport of the meridional overturning circulation, yet uncertainty exists regarding the distribution and physical mechanisms of this mixing. This study uses a highly-idealized, single-hemisphere model of …
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Diagnostics of diapycnal diffusion in z-level ocean models
In general ocean circulation models (OGCMs) diapycnal diffusion arises not<br/>only from the discretisation of the explicit diffusion, but also by numerically<br/>induced diffusion, caused, e.g., by common discretisations of advective<br/>transport.<br/>In the present study, three different …
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Diapycnal Mixing and Mass Transfer in Western Boundary Currents
… of nine isopycnal layers reveal significant diapycnal mixing between upper-thermocline and surface waters in the sector of the Stream between the Florida Straits and the Mid-Atlantic Bight. A two-box model of the nutrient-depleted surface layers (σ<sub>t</sub> < 26.8) and the nutrient-rich …
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Diapycnal advection by double diffusion and turbulence in the ocean
Observations of diapycnal mixing rates are examined and related to diapycnal advection for both double-diffusive and turbulent regimes. The role of double-diffusive mixing at the site of the North Atlantic Tracer Release Experiment is considered. The strength of salt-finger mixing is analyzed in …
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Diapycnal advection by double diffusion and turbulence in the ocean
Observations of diapycnal mixing rates are examined and related to diapycnal advection for both double-diffusive and turbulent regimes. The role of double-diffusive mixing at the site of the North Atlantic Tracer Release Experiment is considered. The strength of salt-finger mixing is analyzed in …
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Sensitivity of climate change to diapycnal diffusivity in the ocean
The diapycnal diffusivity of the ocean is one of the least known parameters in cur- rent climate models. Measurements of this diffusivity are sparse and insufficient for compiling a global map. Inferences from inverse methods and energy budget calculations suggests as much as a factor of 5 …
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The Role of diapycnal mixing in coupled atmosphere-ocean general circulation models
The value of ocean diapycnal diffusivity (v) sets the rate at which dense bottom water can be mixed<br/>up through the stratified water column and thus plays an important role in the meridional overturning<br/>circulation (MOC). Previous idealised experiments and simplified theory suggest that the …
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Mixing in stably stratified turbulent flows: improved parameterizations of diapycnal mixing in oceanic flows
… to inhibit the vertical motion. In such flows, diapycnal mixing, i.e. mixing of fluid across the isopycnal surfaces of constant density, plays a crucial role in the flow dynamics. In numerical models of large scale flows, turbulent mixing is inherently a small scale phenomenon that is difficult …
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A study of diapycnal mixing in the Southern Ocean using a tracer release experiment and numerical models
The Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) includes a tracer release experiment and microstructure programme with the aims of diagnosing the strength and variability of mixing in the Southern Ocean. Here numerical models are used to advect and diffuse a tracer in …
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Impacts of double-diffusive processes on the thermohaline circulation
… rate (and the poleward heat transport) on the diapycnal diffusivity. For any given external forcing, there is only one equilibrium state for the thermohaline circulation. (b) Under "flux" boundary conditions, there is a half power law dependence of the meridional overturning rate on the …
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Impacts of double-diffusive processes on the thermohaline circulation
… rate (and the poleward heat transport) on the diapycnal diffusivity. For any given external forcing, there is only one equilibrium state for the thermohaline circulation. (b) Under "flux" boundary conditions, there is a half power law dependence of the meridional overturning rate on the …
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The production of temperature and salinity variance and covariance : implications for mixing
… density (isopycnal) or across those lines (diapycnal). The contribution of these processes to the total mixing rate in the ocean can be estimated from the large-scale forcing by evaluating the production of thermal variance, salinity variance and temperature-salinity covariance. Here, I use …
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The production of temperature and salinity variance and covariance : implications for mixing
… density (isopycnal) or across those lines (diapycnal). The contribution of these processes to the total mixing rate in the ocean can be estimated from the large-scale forcing by evaluating the production of thermal variance, salinity variance and temperature-salinity covariance. Here, I use …
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Aspects of southern ocean transport and mixing
… have shown that the spatial variability of diapycnal diffusivity, which represents the rate at which deep water returns to shallower depths by means of turbulent diapycnal mixing, is a critical factor controlling the strength and structure of the circulation. Efforts are therefore ongoing to …
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The roles of mixing, geothermal heating, and surface buoyancy forcing in ocean meridional overturning dynamics
… system's scaling behavior, the consequences of diapycnal mixing location, the impact of deep buoyancy fluxes, and the importance of the surface restoring timescale are considered. As required by advective-diffusive balance, upwelling across isopycnals in low latitudes occurs where diapycnal …
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Hydrography and flow in the rift valley of the Mid-Atlantic Ridge
… axes of midocean ridges include high rates of diapycnal mixing associated with the rough topography and high-temperature hydrothermal circulation, a major source for a number of chemical constituents of the ocean.<br/><br/>Physical data sets from the rift valley of two connected segments of the …
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Influence of Mesoscale Eddies on the Deep Ocean Dynamics over the East Pacific Rise near 10N
… finescale parameterization model, the deep ocean diapycnal diffusivity over the ridge crest was estimated. The estimated diapycnal diffusivity shows variation on the subinertial time scale. In particular, the measurements imply a significant increase in diapycnal diffusivity near the seafloor …
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Time-Lapse Volumetric Seismic Imaging of a Major Oceanic Front and Submesoscale Coherent Vortices at South Atlantic Ocean
… noise sub-ranges. The spatial variation of diapycnal diffusivity is estimated by fitting the turbulent sub-range. Results show that diapycnal diffusivity varies between \(O(10^{-5})\) and \(O(10^{-3}) \text{ m}^2 \text{ s}^{-1}\) across the frontal region with anomalously low diffusivities …
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Lagrangian study of the Southern Ocean circulation
… which includes the investigation of the role of diapycnal mixing and the impact of short and long time variability in the flow. Although we show that the flow of particles in the 3-D model is predominantly isopycnal, we find that particles that are forced to remain on isopycnals lead to approx. …
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Driving the ocean's overturning : an adjoint sensitivity study
… ocean heat and freshwater flux, wind stress and diapycnal mixing perturbations in the North Atlantic are likely to have the greatest impact on the meridional overturning and its heat transport. The adjoint model provides clear identification of the physical mechanisms which can influence the …
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