The mean circulation of the southwestern Mediterranean Sea: Algerian Gyres

This is a study about the general circulation of the southwestern Mediterranean Sea based on observations of currents carried out in the southwestern Mediterranean Sea in the framework of the Mass Transfer and Ecosystem Response (MATER) program (EEC/MAST3 program). From July 1997 to August 2002, profiling floats (MEDPROF experiment), isobaric floats (LIWEX experiment), and moored current meters (ELISA experiment) give evidence of two large-scale barotropic cyclonic circulations, the here-called Western and Eastern Algerian Gyres, centered around [3730′N, 230′E] and [3830′N, 600′E], respectively. These gyres have typical horizontal scales of 100–300 km and are characterized by orbital velocities of about 5 cm/s corresponding to rotational periods of about 4 months. They are strongly related to the bottom topography of the basin and to the planetary vorticity gradient: closed f/H isocontours (f is the planetary vorticity, H the water depth) correspond to the locations of the gyres and favor such circulations as free geostrophic modes. A linear and barotropic model is used to investigate the possibility of wind driving, but the results suggest that the wind stress is not responsible for establishing such circulations. The boundary currents flowing along the continental slope of Africa, Sardinia, and the Balearic Islands are proposed to be the main drivers of these gyres

Variabilité spatiale et temporelle de la circulation superficielle dans la région du courant Algerien

Memoria de tesis doctoral presentada por Catherine Bouzinac para optar al grado de Doctora por la Université Pierre et Marie Curie, realizada bajo la dirección del Dr. Jordi Font Ferré del Institut de Ciències del Mar (ICM-CSIC).-- 122 pagesPeer Reviewe

The annual cycle of sea level in the Western Mediterranean Sea

1 page, 1 figureAn estimation of the annual sea level variations in the different basins of the western Mediterranean has been addressed using sea level anomalies derived from satellite altimeters and sea surface temperatures from infrared imagery. Empirical orthogonal function analysis on SLA allows estimating the seasonal dynamic height and the steric effect. The remaining signal is used to examine the annual cycles of sea level due to water mass budget variations, mesoscale oceanic variability and atmospheric forcingPeer reviewe

Simultaneous Estimation of Ocean Tides and Underwater Topography in the Weddell Sea

A new model for theM2, S2, K1, and O1 tides in the Weddell Sea is developed by assimilating CryoSat-2 data into a barotropic tide model. A variational approach is used, which explicitly allows for errors in the water depth, that is, the bottom topography in open water and the water column thickness under floating ice shelves, so that an optimized estimate of the topography is obtained together with the tidal fields. In preparation for assimilation, the sensitivity of the tidal elevation to the interfacial drag at the sea floor and the ice-water interface (under the floating ice shelves) is investigated; this motivates the development of a new drag parameterization which is more accurate and physically plausible in comparison with the interfacial drag alone. The assimilation of CryoSat-2 data into the model results in tidal elevations with essentially the same accuracy as previous estimates, which is demonstrated by comparisons with independent in situ data and withheld CryoSat-2 data. The novelty of the present tidal estimates is that they are consistent with well-defined dynamics based on the Laplace Tidal Equations—augmented with the new parameterization of drag—and modifications of the prior estimate of underwater topography and water column thickness. Analysis of the sensitivity to the topography finds that, at this level of precision, the topography is not uniquely determined by the observed data

SMOS Validation and the COSMOS Campaigns

International audienceThe Soil Moisture and Ocean Salinity (SMOS) mission is a joint ESA-CNES (F)-CDTI (E) mission within the ESA Living Planet Program, and it was the second ESA Earth Explorer Opportunity Mission to be selected. The mission objectives of SMOS are to provide soil moisture and ocean salinity observations for weather forecasting, climate monitoring, and the global freshwater cycle. This paper will describe the scientific campaigns performed to date, as well as the plans for the on-orbit calibration and validation activitie