Search Results
You are looking at 1 - 3 of 3 items for :
- Author or Editor: Neville Smith x
- Journal of Physical Oceanography x
- Refine by Access: All Content x
Abstract
A two-dimensional primitive equation model is developed to study the thermohaline circulation of the Southern Ocean. The primary objectives are to identify those elements of the ocean climate model important for the thermohaline balance, and to assess the capability of the numerical formulations. The simplified configuration adopted here permits extended runs from rest to equilibrium for a variety of configurations and parametric conditions.
The model is driven by surface flux of momentum, heat and salt, and is implemented with and without the dynamic component in order to delineate important thermodynamic interactions. Additional experiments analyze the effects of seasonal forcing versus annual mean conditions, the eddy coefficient parameterizations, resolution, and convective adjustment schemes.
Reasonable qualitative agreement is found between the model and observations. The fundamental climatic balance is characterized by downward and poleward diffusion of heat, predominantly by diffusive processes, and subsequent convection at high latitudes. The balance is sensitive to seasonal effects, particularly salt-forced convection in winter, and the details of the parameterizations. The convection and diffusion representations are critical for Antarctic water mass formation and frontogenesis as they not only determine the large-scale climatic environment, but also the seasonal production rates of various water masses.
Abstract
A two-dimensional primitive equation model is developed to study the thermohaline circulation of the Southern Ocean. The primary objectives are to identify those elements of the ocean climate model important for the thermohaline balance, and to assess the capability of the numerical formulations. The simplified configuration adopted here permits extended runs from rest to equilibrium for a variety of configurations and parametric conditions.
The model is driven by surface flux of momentum, heat and salt, and is implemented with and without the dynamic component in order to delineate important thermodynamic interactions. Additional experiments analyze the effects of seasonal forcing versus annual mean conditions, the eddy coefficient parameterizations, resolution, and convective adjustment schemes.
Reasonable qualitative agreement is found between the model and observations. The fundamental climatic balance is characterized by downward and poleward diffusion of heat, predominantly by diffusive processes, and subsequent convection at high latitudes. The balance is sensitive to seasonal effects, particularly salt-forced convection in winter, and the details of the parameterizations. The convection and diffusion representations are critical for Antarctic water mass formation and frontogenesis as they not only determine the large-scale climatic environment, but also the seasonal production rates of various water masses.
Abstract
The vertical eddy mixing formulations employed in the K-theory model of Pacanowski and Philander and in second-moment closure models are compared for an equatorial Pacific Ocean simulation. The Pacanowski and Philander model is found to be mainly driven by changes in the stratification rather than shear-generated instabilities, and the position and width of the mixing transition zone between high and low mixing values is found to be sensitive to the parameters of the model. In the second-moment closure models the master length scale limit effectively determines the threshold of the mixing zone, while the inclusion of storage, advection, and diffusion terms in the turbulent kinetic energy equation affects both the position and extent of the transition zone. Viscous mixing is more intense than diffusive mixing in the Pacanowski and Philander scheme, but in the second-moment closure models the reverse tends to be true. As expected, there is no simple functional relationship between the gradient Richardson number and the intensity of mixing in the second-moment closure schemes.
Abstract
The vertical eddy mixing formulations employed in the K-theory model of Pacanowski and Philander and in second-moment closure models are compared for an equatorial Pacific Ocean simulation. The Pacanowski and Philander model is found to be mainly driven by changes in the stratification rather than shear-generated instabilities, and the position and width of the mixing transition zone between high and low mixing values is found to be sensitive to the parameters of the model. In the second-moment closure models the master length scale limit effectively determines the threshold of the mixing zone, while the inclusion of storage, advection, and diffusion terms in the turbulent kinetic energy equation affects both the position and extent of the transition zone. Viscous mixing is more intense than diffusive mixing in the Pacanowski and Philander scheme, but in the second-moment closure models the reverse tends to be true. As expected, there is no simple functional relationship between the gradient Richardson number and the intensity of mixing in the second-moment closure schemes.
Abstract
A simple, frictional, linear model is used to study the motion of the Gull Stream over the continental shelf. It is found that the combination of frictional and topographic effects may provide a further mechanism by which the observed separation of the Gulf Stream may be achieved.
The model predicts separation in the form of a classical separated boundary layer and interrelates the slope of the bottom with the position of separation. Counter-circulations northwest of the stream and increased northward transport of the current are also predicted.
Abstract
A simple, frictional, linear model is used to study the motion of the Gull Stream over the continental shelf. It is found that the combination of frictional and topographic effects may provide a further mechanism by which the observed separation of the Gulf Stream may be achieved.
The model predicts separation in the form of a classical separated boundary layer and interrelates the slope of the bottom with the position of separation. Counter-circulations northwest of the stream and increased northward transport of the current are also predicted.
