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Spiral Eddies

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  • 1 Department of Mathematics, University of Bergen, Bergen, Norway
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Abstract

Small cyclonic spiral eddies with a scale of 10 km are very frequently observed, both from satellites and space shuttles, at the ocean surface. The authors suggest that they are the sea surface signature of ageostrophic baroclinic instabilities. The spiral-like cyclones generated and evolving in this baroclinic model regime are found to be consistent with the observed spatial and temporal scales. Both modeled and observed spiral eddies are associated with streaks of strong cyclonic shear and convergence. The numerical experiments presented indicate that spiral eddies are restricted to the very upper ocean, and that they are a source of kinetic energy for the larger scale flow.

Current affiliation: Nansen Environmental and Remote Sensing Center, Bergen, Norway

Corresponding author address: Tor Eldevik, Nansen Environmental and Remote Sensing Center, Edv. Griegs vei 3A, N-5059 Bergen, Norway. Email: tor.eldevik@nersc.no

Abstract

Small cyclonic spiral eddies with a scale of 10 km are very frequently observed, both from satellites and space shuttles, at the ocean surface. The authors suggest that they are the sea surface signature of ageostrophic baroclinic instabilities. The spiral-like cyclones generated and evolving in this baroclinic model regime are found to be consistent with the observed spatial and temporal scales. Both modeled and observed spiral eddies are associated with streaks of strong cyclonic shear and convergence. The numerical experiments presented indicate that spiral eddies are restricted to the very upper ocean, and that they are a source of kinetic energy for the larger scale flow.

Current affiliation: Nansen Environmental and Remote Sensing Center, Bergen, Norway

Corresponding author address: Tor Eldevik, Nansen Environmental and Remote Sensing Center, Edv. Griegs vei 3A, N-5059 Bergen, Norway. Email: tor.eldevik@nersc.no

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