Nonlinear Processes in Oceanic and Atmospheric Flows

Presentation

Mesoscale, open-ocean anticyclones, vortex Rossby waves and strong vertical velocities

Author: Inga Koszalka, University of Oslo.

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Oral or poster: Oral presentation

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Mesoscale, open-ocean anticyclones, vortex Rossby waves and strong vertical velocities

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Abstract:
I study numerically the dynamics of mesoscale vortices by using a high-resolution, primitive-equation circulation model (Regional Ocean Modelling System, ROMS) in the context of a wind-forced, stably-stratified, open ocean on a f-plane and in the regime of a small internal Rossby deformation radius. Many properties of the simulated flow, in terms of wavenumber spectra, topology, velocity distributions and dispersion statistics, are found to be similar to these of two-dimensional turbulence. In contrast to quasi-geostrophic approximation, the dynamics features a strong cyclone-anticyclone asymmetry and an unexpectedly complex structure of the vertical velocity field related to the presence of vortices, filaments, vortex Rossby waves, as well as their interactions with Ekman circulation and inertial-internal waves. The vertical motions reach up to 100 m/day in magnitude and are responsible for large vertical excursions of Lagrangian tracers.

*Satellite images from NASA and ESA

Nonlinear Processes in Oceanic and Atmospheric Flows. July 2-4, 2008. Castro Urdiales, Cantabria, Spain.