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Abstract
The development of mixed layer models in so-called density coordinates is discussed. Density coordinates, or isopycnal coordinates as they are sometimes called, are becoming increasingly popular for use in ocean models due to their highly desirable adiabatic properties. In contrast, almost all existing mixed layer models assume a continuous density variable and are therefore somewhat inconsistent with the density coordinate philosophy. Many existing isopycnal models attempt to join standard surface mixed layer models to density coordinate interior models, and it is known that problems can arise in the physical behavior of the resulting system. The problem of mixed layer model development is approached here by adopting a density coordinate framework at the outset, thereby generating a surface layer model whose construction is entirely consistent with that of existing interior density coordinate models. Examples of quantitative and qualitative behavior are presented and argued to be encouraging.
Abstract
The development of mixed layer models in so-called density coordinates is discussed. Density coordinates, or isopycnal coordinates as they are sometimes called, are becoming increasingly popular for use in ocean models due to their highly desirable adiabatic properties. In contrast, almost all existing mixed layer models assume a continuous density variable and are therefore somewhat inconsistent with the density coordinate philosophy. Many existing isopycnal models attempt to join standard surface mixed layer models to density coordinate interior models, and it is known that problems can arise in the physical behavior of the resulting system. The problem of mixed layer model development is approached here by adopting a density coordinate framework at the outset, thereby generating a surface layer model whose construction is entirely consistent with that of existing interior density coordinate models. Examples of quantitative and qualitative behavior are presented and argued to be encouraging.
Abstract
The numerical solution of the vertical advection–diffusion equation in layered coordinates is revisited. The objectives of this work are to propose a generalization of the discontinuous layered representation of the ocean tracer field to higher-order, smoother representations (while retaining the quasi-Lagrangian character of the coordinate) and compare the solutions generated by several approaches in order to illustrate their respective advantages and disadvantages. The one-dimensional advection–diffusion equation is chosen as a test bed for layered coordinates because ocean simulation for climatic purposes requires the inclusion of dianeutral diffusive processes.
The layered approach is generalized by replacing the traditional stack of well-mixed layers by stacks of piecewise smooth profiles. All the well-known properties of quasi-Lagrangian coordinates are retained. Comparisons of the quasi-Lagrangian solutions with coarse- and fine-resolution fixed grid solutions illustrates the efficiency of the adaptive, quasi-Lagrangian coordinate.
Abstract
The numerical solution of the vertical advection–diffusion equation in layered coordinates is revisited. The objectives of this work are to propose a generalization of the discontinuous layered representation of the ocean tracer field to higher-order, smoother representations (while retaining the quasi-Lagrangian character of the coordinate) and compare the solutions generated by several approaches in order to illustrate their respective advantages and disadvantages. The one-dimensional advection–diffusion equation is chosen as a test bed for layered coordinates because ocean simulation for climatic purposes requires the inclusion of dianeutral diffusive processes.
The layered approach is generalized by replacing the traditional stack of well-mixed layers by stacks of piecewise smooth profiles. All the well-known properties of quasi-Lagrangian coordinates are retained. Comparisons of the quasi-Lagrangian solutions with coarse- and fine-resolution fixed grid solutions illustrates the efficiency of the adaptive, quasi-Lagrangian coordinate.
Abstract
The design and implementation of a midlatitude basin-scale coupled climate model are described. The development of the model is motivated by the clear indications of important low-frequency midlatitude ocean variability in ocean-only models and the lack of the same in coupled climate models. Currently, the best comprehensive coupled climate models run at resolutions far coarser than those needed to model intrinsic ocean variability. The model presented here is an attempt to explicitly include ocean eddies within the framework of an idealized climate setting. It is proposed that the model will help resolve how intrinsic ocean variability is altered by coupling and the extent to which such variability may force the climate. The objective of this paper is to describe the theory behind the model formulation and its implementation.
The basic model consists of a quasigeostrophic channel atmosphere coupled to a simple, rectangular quasigeostrophic ocean. Heat and momentum exchanges between the ocean and the atmosphere are mediated via mixed-layer models, and the system is driven by steady, latitudinally dependent incident solar radiation. Model spinup is described, some basic descriptors of the solution are discussed, and it is argued that the model exhibits skill in capturing essential features of the midlatitude climate system.
Abstract
The design and implementation of a midlatitude basin-scale coupled climate model are described. The development of the model is motivated by the clear indications of important low-frequency midlatitude ocean variability in ocean-only models and the lack of the same in coupled climate models. Currently, the best comprehensive coupled climate models run at resolutions far coarser than those needed to model intrinsic ocean variability. The model presented here is an attempt to explicitly include ocean eddies within the framework of an idealized climate setting. It is proposed that the model will help resolve how intrinsic ocean variability is altered by coupling and the extent to which such variability may force the climate. The objective of this paper is to describe the theory behind the model formulation and its implementation.
The basic model consists of a quasigeostrophic channel atmosphere coupled to a simple, rectangular quasigeostrophic ocean. Heat and momentum exchanges between the ocean and the atmosphere are mediated via mixed-layer models, and the system is driven by steady, latitudinally dependent incident solar radiation. Model spinup is described, some basic descriptors of the solution are discussed, and it is argued that the model exhibits skill in capturing essential features of the midlatitude climate system.
