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| Titel |
Surface signature of Mediterranean water eddies in the Northeastern Atlantic: effect of the upper ocean stratification |
| VerfasserIn |
I. Bashmachnikov, X. Carton |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 8, no. 6 ; Nr. 8, no. 6 (2012-11-01), S.931-943 |
| Datensatznummer |
250006009
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| Publikation (Nr.) |
 copernicus.org/os-8-931-2012.pdf |
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| Zusammenfassung |
Meddies, intra-thermocline eddies of Mediterranean water, can often be
detected at the sea surface as positive sea-level anomalies. Here we study
the surface signature of several meddies tracked with RAFOS floats and AVISO
altimetry.
While pushing its way through the water column, a meddy raises isopycnals
above. As a consequence of potential vorticity conservation, negative
relative vorticity is generated in the upper layer. During the initial
period of meddy acceleration after meddy formation or after a stagnation
stage, a cyclonic signal is also generated at the sea-surface, but mostly
the anticyclonic surface signal follows the meddy.
Based on geostrophy and potential vorticity balance, we present theoretical
estimates of the intensity of the surface signature. It appears to be
proportional to the meddy core radius and to the Coriolis parameter, and
inversely proportional to the core depth and buoyancy frequency. This
indicates that surface signature of a meddy may be strongly reduced by the
upper ocean stratification. Using climatic distribution of the stratification
intensity, we claim that the southernmost limit for detection in altimetry of
small meddies (with radii on the order of 10–15 km) should lie in the
subtropics (35–45° N), while large meddies (with radii of
25–30 km) could be detected as far south as the northern tropics
(25–35° N). Those results agree with observations. |
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