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| Titel |
The Azores Current, from Madeira to the Gulf of Cadiz |
| VerfasserIn |
A. Aguiar, A. Peliz, A. Teles-Machado, A. Cordeiro Pires |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026282
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| Zusammenfassung |
| The Azores current is thought to be a zonal jet which originates as a branch of the Gulf
Stream, crosses the Mid-Atlantic Ridge south of Azores and flows eastwards until
reaching the Gulf of Cadiz. Recent observational and theoretical studies indicate
that this current undergoes very little seasonal variations, maintains a transport of
3 - 4 Sv at its eastern end and has a counter-current at north. Such observations
suggest that the current can be forced by Mediterranean Overflow and beta-plume
models have shown that the entrainment of Mediterranean Water in the Atlantic may
induce large-scale circulation structures which could explain the aforementioned
observations.
We have been analysing Absolute Dynamic Topography (ADT) maps as well as time
series of Sea Level Anomaly (SLA) maps in the region between 10oE–40oW and
30oN–40oN. Preliminary results from ADT provide weak observational support for the
presence of a beta-plume induced circulation cell in the Gulf of Cadiz, while a ~ 15 yrs mean
SLA map reveals a coherent wavemode pattern along the 34o N parallel. To better understand
the dynamics of the Azores current, we have also been studying the mesoscale activity in this
region using in situ data (SVP). Our records show that eddies in this region have an average
period of 16 days and diameters around 70 km. The eddy centre propagation speeds are ~ 2
cm s-1, whereas swirl velocities are in the range 6 - 40 cm s-1 with corresponding EKE of
20 - 900 cm2 s-2. In general, the eddies tend to move westwards and can remain
coherent for as long as ~ 200 days while travelling distances up to ~ 500 km.
Furthermore, when going from northern to southern latitudes it was observed a
decrease (increase) in the number of anticyclones (cyclones) – an asymmetry that is in
agreement with results from previous theoretical studies which are able to explain the
observed mesoscale features assuming that the Azores Front is baroclinically unstable. |
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