Advances in coastal altimetry over the Northwestern Mediterranean
Jérôme Bouffard1, Stefano Vignudelli2, Florent Lyard1, Florence Birol1, Patrick Marsaleix3,
Laurent Roblou4, Yves Menard5, Gian Pietro Gasparini6, Giuseppe Manzella7 and Paolo
Cipollini8
1
Laboratoire d'Etude en Géophysique et Océanographie Spatiale, 14 Av. Edouard Belin, 31400
Toulouse – France. E-mail: bouffard@notos.cst.cnes.fr
2
Consiglio Nazionale delle Ricerche, Istituto di Biofisica, Area Ricerca CNR San Cataldo, 56127
Pisa, Italy. E-mail: vignudelli@pi.ibf.cnr.it
3
Laboratoire d'Aérologie, 14 Av. Edouard Belin, 31400 Toulouse – France
4
Noveltis, Parc Technologique du Canal 2, Av. de l'Europe, 31520 Ramonville-Saint-Agne,
France
5
CNES, 18, Av. Edouard Belin, 31055, Toulouse, France
6
CNR, Istituto di Scienze del Mare, Forte Santa Teresa, 19036 La Spezia, Italy
7
ENEA, Centro Ricerche Ambiente Marino, Forte Santa Teresa, 19036 La Spezia, Italy
8
National Oceanography Centre, European Way, SO14 3ZH, Southampton, UK
We describe the motivations and outcomes of 10 years of research into applications of
altimetry in the Northwestern Mediterranean. The activities had two specific and complementary
purposes: a) to contribute to the oceanographic knowledge of the area and b) to assess the
applicability of altimeter techniques in coastal/marginal systems. The region is a perfect site for
such investigations, in virtue of the favourable location of altimetric tracks and cross-over points,
combined with the availability of long-term in-situ observations from a number of instruments
including currentmeters, tide gauges and bottom pressure recorders. As such, the sites of Senetosa,
Macinaggio and Capraia in the area have been chosen for cal/val activities and hydrographic
campaigns in the framework of the joint French-Italian ALBICOCCA (ALtimeter-Based
Investigations in COrsica, Capraia and Contiguous Areas) project.
We briefly discuss some of the oceanographic issues that have been addressed with the help
of altimetry, for instance what drives the flow along the Corsica channel, which exhibits a marked
seasonal and interannual variability. Capturing such variability is crucial to the understanding of
physical coastal processes in the North Western Mediterranean Sea (hereafter NWM Sea). This is
especially true for the Ligurian-Provençal Current, a coastal current arising from the merging of
the Western and Eastern Corsica Current. This slope current, which is one of the major dynamic
structures in the NWM Sea, has a spatial and temporal variability partially driven by the Corsica
channel dynamic. Altimetry is well suited to the study of the general circulation in the open ocean,
however it is still a challenging issue for coastal studies such as in the NWM because the
dynamic is much more complex and characterized by smaller spatial and temporal scales.
Moreover, standard altimetric products require tools and correction models, which are tailored for
the deep ocean and not optimized for the coastal area.
Thus, an important aspect of the research activity consisted of assessing the extent to which
altimetry data can be employed in the area, and devising any possible improvement in the data
processing chain and in the retrieval of the geophysical parameters in order to make altimetry
more applicable. We describe the adopted processing strategy, which includes local corrections,
and the comparison of the retrieved parameters with in situ sea level anomalies and surface
velocity anomalies from moorings, showing a good level of agreement. The spatial and temporal
scales accessible through these multi-sensor observing systems are then compared with the 3D
coastal model Symphonie in order to show their capabilities to improve our knowledge of the
coastal area in the NWM Sea.