Wednesday, May 26

Geometric Approximation Methods in Ocean Modeling

10:00 AM-12:00 PM
Room: Ballroom II

One well-documented feature of global ocean circulation is its large variability in regions adjacent to coherent western-intensified currents such as the Kuroshio Current and the Gulf Stream. This variability limits predictability of mean properties such as the poleward heat transport, which in turn affects the accuracy in determining the Earth's climate in coupled ocean-atmosphere models. Current general circulation models (GCMs) typically underestimate this variability greatly when compared to available observations (e.g., Topex / Poseidon). The physical origins of variability are doubtless complex in detail and include delicate potentially unstable feedback in the air-sea interaction. Variability in current GCMs may be constrained by inadequate parameterization and limited dynamical range which, at 25 km, (in global simulations) is at best marginal with respect to mesoscale physics. In this respect, the considerable recent interest among the oceanographic community in decadal and longer-period variability of the circulation only underscores the need to understand the underlying mathematical and geometrical structure in simulating complex systems such as ocean circulation and the air-sea interaction responsible for our climate. The speakers will discuss their individual approaches and recent progress in studying various dynamical systems aspects of this problem.

Organizer: Darryl D. Holm
Los Alamos National Laboratory

10:00-10:25 Extended Geostrophic Euler-Poincaré Ocean Models
J. S. Allen and P. A. Newberger, Oregon State University; and Darryl D. Holm, Organizer
10:30-10:55 Successive Bifurcations in the Oceans' Wind-driven Circulation
Michael Ghil, University of California, Los Angeles
11:00-11:25 Dynamical Systems Challenges in Assessing Ocean Transport
Christopher K. R. T. Jones, Brown University
11:30-11:55 Material Dispersion in Wind-driven Ocean Gyre
James C. McWilliams and Pavel Berloff, University of California, Los Angeles

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MMD, 2/12/99
LMH, 1/11/99; tjf, 2/3/99