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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2008.07.014 Byline: Francesco d'Ovidio (a)(b), Jordi Isern-Fontanet (c), Cristobal Lopez (d), Emilio Hernandez-Garcia (d), Emilio Garcia-Ladona (e) Abstract: Transport and mixing properties of surface currents can be detected from altimetric data by both Eulerian and Lagrangian diagnostics. In contrast with Eulerian diagnostics, Lagrangian tools like the local Lyapunov exponents have the advantage of exploiting both spatial and temporal variability of the velocity field and are in principle able to unveil subgrid filaments generated by chaotic stirring. However, one may wonder whether this theoretical advantage is of practical interest in real-data, mesoscale and sub-mesoscale analysis, because of the uncertainties and resolution of altimetric products, and the non-passive nature of biogeochemical tracers. Here we compare the ability of standard Eulerian diagnostics and the finite-size Lyapunov exponent in detecting instantaneous and climatological transport and mixing properties in the south-western Mediterranean. By comparing with sea-surface temperature patterns, we find that the two approaches provide similar results for slowly evolving eddies like the first Alboran gyre. However, the Lyapunov exponent is also able to predict the (sub-)mesoscale filamentary processes occurring along the Algerian current and above the Balearic Abyssal Plain. Such filaments are also observed, with some mismatch, in sea-surface temperature patterns. Climatologies of Lyapunov exponents do not show any compact relation with other Eulerian diagnostics, unveiling a different structure even at the basin scale. We conclude that filamentation dynamics can be detected by reprocessing available altimetric data with Lagrangian tools, giving insight into (sub-)mesoscale stirring processes relevant to tracer observations and complementing traditional Eulerian diagnostics. Author Affiliation: (a) Laboratoire d'Oceanographie et du Climat: Experimentation et Approches Numeriques, IPSL, Paris, France (b) Institute of Complex Systems, Paris Ile-de-France (ISC-PIF), France (c) Laboratoire d'Oceanographie Spatiale, Ifremer, Plouzane, France (d) Instituto de Fisica Interdisciplinar y Sistemas Complejos IFISC (CSIC-UIB), Campus Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain (e) Institut de Ciencies del Mar, CSIC, Passeig Maritim de la Barceloneta 37-43, E-08003 Barcelona, Spain Article History: Received 25 October 2007; Revised 25 July 2008; Accepted 29 July 2008

Infrared satellite imagery and drifting buoy trajectories have provided new data on mesoscale phenomena produced by the Mediterranean Sea's Algerian Current. These include meander of current linked to surface anticyclonic eddies within its crest, deep anticyclonic eddies below the meander, and transitory surface cyclonic eddies occurring upstream from the crest.

A year-long study of deep slope currents and particulate matter concentrations on the Barcelona continental margin in the Mediterranean Sea is discussed. Near bottom slope currents in and around the Foix submarine canyon showed the influence of bottom topography.