GALCIT Home Page
| Fluids Seminar Page |
Earth and Environmental Sciences
Los Alamos National Laboratory
Abstract-
Mesoscale eddies (50-100 km scales) play an important role in
determining the overall circulation of the world oceans and are
intimately related to the transport of variables like heat, vorticity
and momentum. Since a proper resolution of these eddy fields in long
term simulations is computationally prohibitive, it is important to be
able to parameterize their effects on mean flow. In this talk, we
will consider two idealized setups to study such eddy fields. First,
we will briefly present simulations of a bouyancy driven,
baroclinically-unstable zonal flow in a channel and discuss its
salient features. Next, and in more detail, we will consider the case
of a double-gyre wind forced barotropically-unstable flow in a
rectangular midlatitude ocean basin. In this latter case---a much
studied classical problem---we show that a new component of time-mean
flow, which is eddy-driven, arises when dissipation is low enough.
Finally, we present models for such a flow in which eddy effects are
parameterized. One of these uses nonlinear dispersion to model the
effects of eddies on mean flow and is based on the ideal mean flow
fluid model of Holm, Marsden, and Raitu (PRL 80, 4273--4277, 1998).
|
GALCIT Home Page
|
|