HR: 0800h
AN: OS41D-0507    [Abstracts]
TI: Instabilities Along a Coastal Downwelling Front
AU: * Whitney, M M
EM: whitney@coas.oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences Oregon State University, 104 COAS Admin. Bldg., Corvallis, OR 97331-5503 United States
AU: Allen, J S
EM: jallen@oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences Oregon State University, 104 COAS Admin. Bldg., Corvallis, OR 97331-5503 United States
AB: This research studies the instabilities that develop along stratified continental shelves under downwelling conditions. The generation and evolution of the instability field is investigated for idealized situations using the ROMS hydrodynamic model. The model domain has a straight coast and constant shelf slope. The model is initialized with constant stratification and forced with a downwelling-favorable wind impulse. This wind impulse is spatially uniform except for small perturbations introduced to excite instabilities. Three types of instabilities develop initially: baroclinic instabilities arise near the surface in the downwelling jet, shear instabilities grow along the shoreward edge of the jet, and baroclinic instabilities form within the frictional bottom boundary layer. The boundary layer instabilities begin as symmetric instabilities and are sensitive to bottom slope and friction. As the instability field matures, the dominant wavelength increases from O(10 km) to O(100 km) and shear instabilities become most important. Instabilities directly extract a small percentage of energy from the mean flow. The instabilities also lead to increased dissipation that slows the downwelling jet and decreases isopycnal slopes.
DE: 4219 Continental shelf processes
DE: 4255 Numerical modeling
DE: 4528 Fronts and jets
DE: 3220 Nonlinear dynamics
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting