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| Titel |
A statistical study of MO eddies in a 20 yrs high resolution simulation |
| VerfasserIn |
A. Barbosa Aguiar, A. Peliz, A. Teles-Machado, X. Carton |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250066263
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| Zusammenfassung |
| The Mediterranean Outflow (MO) has been modelled using a realistic model (ROMS) of the
circulation off southwestern Iberian Peninsula. The model was run at high resolution for 20
years. As the MO flows along the Portuguese coastal shelf it destabilizes and gives origin to
eddies with a Mediterranean Water (MW) core. Such eddies can be easily detected due to
their large salinity and temperature anomalies. Several of these eddies have been studied in
the ocean using in situ measurements and floaters. Although most of the structures with a
MW core signature are anticyclones (AC) and usually referred to as meddies, some
cyclones (C) have also been observed exhibiting weaker anomalies and shallower cores
than typical meddies. These vortices are lense-like shaped, with a characteristic
dynamic horizontal extension of 100 km but only 1 km long in depth. They are
long-lived structures (2 yrs on average) that often break up after colliding with
seamounts and are thus believed to be important for MW dispersion in the Iberian
basin.
Here we present a statistical study of modelled eddies and compare our results with
observations. Both AC and C eddies with a MW core have been detected in a 3:1
ratio approximately. Using an eddy tracking algorithm (based on the Okubo-Weiss
parameter) we were able to track the eddies through their lifetime and this allowed us to
identify the main formation sites and main paths of propagation. We estimate a rate of
formation of 15-20 yr-1, AC and C altogether, which is in agreement with previous
observation-based estimates of 17 meddies yr-1. Our results suggest that there is a higher
incidence of AC (C) formation downstream (upstream) of Cape St Vincent. We
also show the spatial distribution and statistics of the main physical characteristics
of the eddies such as size, lifetime, propagation velocity and distance travelled. |
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