On the influence of submarine ridges on translation and stability of Agulhas rings

Beismann, Jens-Olaf, Käse, Rolf H. and Lutjeharms, J. R. E. (1999) On the influence of submarine ridges on translation and stability of Agulhas rings Journal of Geophysical Research: Oceans, 104 (C4). pp. 7897-7906. DOI 10.1029/1998JC900127.

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Abstract

A series of experiments with a quasi‐geostrophic model have been carried out to investigate the influence of topographic obstacles on the translatory movement of Agulhas rings. The rings were initialized as Gaussian‐shaped anomalies in the stream function field of a two‐layer ocean at rest. Bottom topography consisted of a meridional ridge of constant height in the middle of the quadratic model domain. The vertical ring structure, the initial ring position, and the height of the ridge were varied. The general northwestward movement of the model eddies has been shown to be modified toward a more equatorward direction by encountering the upslope of the ridge. Sufficient topographic heights and strong slopes can even block the eddies and force them toward a pure meridional movement. During their translation the eddies lose their vertical coherence. After about 150 days the eddy can only be detected by the surface signal, while the lower layer eddy is dispersed by the radiation of Rossby waves. The passage of “young” (regarding the time between their initialization and their contact with the ridge) and energetic eddies is accompanied by the observation of along‐slope currents of significant strength. These may be due to the rectification of radiated Rossby waves at the topographic slope. Only eddies with a significant dynamic signal in the lower layer are influenced by the bottom topography. Strong, shallow eddies over deep lower layers can cross the ridge without strong modification of their translatory movement.

Document Type: Article
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
OceanRep > Institute for Marine Science Kiel
Refereed: Yes
DOI etc.: 10.1029/1998JC900127
ISSN: 2169-9275
Date Deposited: 03 Mar 2008 11:15
Last Modified: 27 Apr 2018 11:00
URI: http://eprints.uni-kiel.de/id/eprint/4813

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