IUGG 2003 Abstract

P01 Western Boundary Currents Wednesday, July 2 AM Location: Site B, Room 18 Presiding Chairs:D.K. Olson, S. Imawaki

TIME [ 930 ] [ P01/02A/B18-003 ]

HIGH REYNOLDS NUMBER MODELLING OF WESTERN BOUNDARY CURRENTS USING FULLY-ADAPTIVE FINITE ELEMENTS

David P. MARSHALL(Department of Meteorology, University of Reading)

Christopher C. PAIN(Department of Earth Science and Engineering, Imperial College, University of London) Matthew PIGGOTT ( Department of Earth Science and Engineering, Imperial College, University of London ) Antony J. H. GODDARD ( Department of Earth Science and Engineering, Imperial College, University of London ) Cassiano R. E. DE OLIVEIRA ( Department of Earth Science and Engineering, Imperial College, University of London ) Adrian P. UMPLEBY ( Department of Earth Science and Engineering, Imperial College, University of London )

Unstructured finite elements present many potential advantages over traditional finite difference methods for modelling the ocean circulation, and in particular western boundary currents. For example they allow for the use of unstructured grids which may both conform well to the bottom topography, and adapt as the flow evolves in order to resolve specific flow features. In this paper, we report on our progress towards developing a 3-dimensional, nonhydrostatic finite element ocean model. One key issue is that standard finite elements fail to represent geostrophic and hydrostatic balance adequately - a strategy for circumventing this problem through a reformulation of the momentum equations will be discussed. Preliminary calculation will be presented for the wind-driven circulation and western boundary currents in closed ocean basins at Reynolds numbers of up to O(104). In contrast to previous calculations, the finite elements are able to properly resolve the thin no-slip sub-layers within the boundary currents, and their detachment in regions of flow separation. The unprecedented richness of the flow structures obtained in such regions will be discussed.