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| Titel |
Geostrophic and ageostrophic circulation of a shallow anticyclonic eddy off Cape Bojador |
| VerfasserIn |
Simón Ruiz, Josep L. Pelegrí, Mikhail Emelianov, Ananda Pascual, Evan Mason |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089207
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| Publikation (Nr.) |
 EGU/EGU2014-3403.pdf |
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| Zusammenfassung |
| A shallow mesoscale anticyclonic eddy, observed south of the Canary Islands with satellite altimetry, has been intensively studied with multi-parametric sampling. Hydrographic data from a CTD installed on an undulating Nu-shuttle platform reveal the presence of a mesoscale anticyclonic eddy of ~125 km diameter. The difference in sea level anomaly (SLA) between the interior and the edge of the eddy, as determined from altimetry, is ~15 cm, which compares well with the maximum dynamic height differences as inferred using a very shallow reference level (130 m). Further, the associated surface geostrophic velocities, of about 35 cm/s in the northeast and southwest edges of the eddy, are in good agreement with direct velocity measurements from the ship. Deep rosette-CTD casts (1500 m depth) confirm that the structure is a shallow eddy extending no deeper than 250 m before the fusion with another anticyclone. The SLA-tendency (temporal rate of change of sea surface height) indicates a clear northwestward migration during the two first weeks of November 2008. Applying an eddy SSH based tracker, the eddy’s velocity propagation is estimated as 4 km/day. Use of the QG-Omega equation diagnoses maximum downward/upward velocities of about ± 2 m/day. The instability of the Canary coastal jet appears to be the mechanism responsible for the generation of the shallow anticyclonic eddy. |
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