HR: 0830h
AN: OS11A-01    [Abstracts]
TI: Topographic Rossby Waves in a Z-Level Ocean Model
AU: * Dukhovskoy, D S
EM: ddmitry@coaps.fsu.edu
AF: Center for Ocean-Atmospheric Prediction Studies, Florida State University, COAPS/FSU, Tallahassee, FL 32306-2840 United States
AU: Morey, S L
EM: morey@coaps.fsu.edu
AF: Center for Ocean-Atmospheric Prediction Studies, Florida State University, COAPS/FSU, Tallahassee, FL 32306-2840 United States
AU: O'Brien, J J
EM: jim.obrien@coaps.fsu.edu
AF: Center for Ocean-Atmospheric Prediction Studies, Florida State University, COAPS/FSU, Tallahassee, FL 32306-2840 United States
AB: Topographic Rossby waves (TRW) play an important role in the ocean dynamics in regions where the slope of the bottom topography is sufficiently large so as to dominate the β-effect. TRW propagate signals in the ocean along the slopes over large distances [Oey and Lee, 2002]. Pacanowski and Gnanadesikan [1998] suggested that when the bottom slope is less than the grid cell aspect ratio (Δz/Δx) in a numerical ocean model with a Z-level vertical coordinate, the model does not accurately resolve topography leading to an inaccurate simulation of topographic waves with a modified dispersion relation. It is important to better understand the consequences of the modelers' choices of vertical grids since coarse vertical resolution ocean models can alter the rate and direction of propagation of waves. Using Navy Ocean Coastal Model, we examine the ability of Z-level models to accurately simulate topographic waves by conducting model experiments with σ-level (terrain following) and Z-level vertical coordinate systems with different vertical resolutions. We will show that Z-level models can accurately reproduce TRWs if the bathymetry is well resolved in the model. Poor vertical resolution leads to an unrealistic representation of the bathymetry, which initiates different waves with different dispersion relations resulting in errors of signal propagation in the model. Also the necessary criteria for the resolution of bathymetry in Z-level models for properly simulating TRW is suggested.
DE: 3210 Modeling
DE: 4219 Continental shelf processes
DE: 4255 Numerical modeling
DE: 4520 Eddies and mesoscale processes
SC: Ocean Sciences [OS]
MN: 2005 Joint Assembly