2004 LOM Workshop

Tuesday 10:20 - 11:30 a.m. Poster Session

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Modeling Gravity Currents in Isopycnal and Quasi-Isopycnal Ocean Circulation Models

Whit Anderson, Paul Schopf
George Mason University
datatrident@mac.com

ABSTRACT

This work investigates several modeling issues related to the representation of deep gravity currents in predominantly isopycnal ocean circulation models. We examine the role of various Richardson-number mixing schemes on the behavior of bottom currents. Previous studies have examined smoothly varying Ri-dependent schemes, and the present study re-affirms the basic results to date. But we extend these examples to consider the relative roles of bottom drag and entrainment mixing in setting the pathways and character of deep plumes. The study examines the implications of vertical resolution on the character of solutions. Richardson-number dependent mixing schemes rely fundamentally on the adequacy of vertical resolution, while global climate simulations place significant limits on the vertical resolution available for global ocean models. The implications of limited vertical resolution on such simulations is discussed. We compare the quasi-isopycnal approach to mixing and the recently developed implicit mixing techniques for isopycnal models. Both methods use the ALE technique for treating separately the processes of horizontal dynamics and vertical remapping of coordinates, but in the first case, vertical diapycnal mixing is solved after horizontal advection but before remapping, while in the latter, vertical remapping is constructed so as to include the effect of mixing.

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LOM Users' Workshop, February 9-11, 2004