Representation of Eddies in Climate Models by a Potential Vorticity Flux.
Abstract
This thesis addresses the parameterization of the heat and momentum transporting properties of eddy motions for use in primitive equation climate models. The approach is to transform the primitive equations to yield the altered transformed Eulerian mean' (TEM) equations. Further, the assumption is made that the eddy motions obey quasigeostrophic dynamics. This yields a framework in which the eddies appear as one term, acting as a body force in the momentum equations. This force manifests itself as a flux of potential vorticity (PV) - a quantity that incorporates both eddy momentum and heat transporting properties. Moreover, the dynamic velocities are those of the residual mean circulation, a much more relevant velocity for understanding heat and tracer transport. Closure for the eddy PV flux is achieved through a flux-gradient relationship, directing it down the large scale PV gradient. The approach is investigated through numerical experiments, which compare a parameterized model with eddy-resolving calculaflons. The results show that the correct momentum transfer, particularly the up gradient, lateral momentum transfer by eddies, is captured in the parameterized model. This approach to parameterization provides a powerful conceptual and practical framework for representing eddies in numerical models of the atmosphere and ocean.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1999
- Accession Number
- ADA369290
Entities
People
- Richard M. Wardle
Organizations
- Woods Hole Oceanographic Institution