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| Titel |
Combined use of glider, radar and altimetry data to study a coastal current in the western Mediterranean Sea |
| VerfasserIn |
Charles Troupin, Ananda Pascual, Arancha Lana, Guillaume Valladeau, Isabelle Pujol, Joaquin Tintoré |
| 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 |
250089557
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| Publikation (Nr.) |
 EGU/EGU2014-3762.pdf |
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| Zusammenfassung |
| The Mediterranean Sea is characterized by a small Rossby radius of deformation, hence
small structures and eddies. The Ibiza Channel, located in the Balearic Sea, is of
particular importance since it controls the exchanges in the western Mediterranean
Sea.
In order to understand and describe the upper ocean dynamics, a multi-sensor/integrated
approach was applied in the Ibiza Channel in the first days of August 2013 during the
G-AltiKa mission. This approach combines:
Sea-level anomaly (SLA) measurements from Saral-AltiKa track no. 16, which
passed west of Ibiza island. 1-Hz and 40-Hz data were considered.
Glider data obtained along the satellite track a few hours after its passage. The
horizontal resolution ranges from 5 km offshore to about 1 km in the coastal
area.
HF radar hourly velocities on a 3km-resolution grid that partially covers the study
region (range up to 74km offshore).
Dynamic height (DH) was derived from the glider temperature and salinity profiles, while
Absolute Dynamic Topography (ADT) was obtained by combining SLA and the new Mean
Dynamic Topography (MDT) jointly produced by CLS and SOCIB. From DH and SLA,
the cross-track velocities were derived using geostrophy relations. Different filters
were applied on SLA data and different reference levels were tested for the DH
computation.
DH and ADT both displayed very weak variations, on the order of 2-3 cm,
along the glider trajectory. The glider- and the altimetry-derived velocities exhibit
the signal of a meander centered at 38.65°N and a narrow coastal current flowing
northward a few kilometers off Ibiza. These computed velocities are on the order of
20cm/s, as confirmed by the HF radar. The time separation between the passage of the
satellite and the glider can explain the discrepancies observed between the two
platforms.
Our results highlight the promising measurements offered by SARAL/AltiKa in the
coastal band. In particular, the satellite was able is able to capture the northern edge of the
meander which lied on a shallow bathymetry, less than 10km from the coast. They also
constitute the first experiment where satellite altimetry and glider measurements were
obtained almost simultaneously on the same track, in a region covered by a HF radar. Such an
approach allows us to process, validate and intercalibrate multi-platform datasets dedicated to
coastal ocean. |
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