Fabien Lefèvre

Collecte Localisation Satellites | CLS · Environment & Climate

The final outcomes and recommendations were discussed at the final session of the workshop and endorsed by review of the workshop report. Final discussion points included whether there is a need for a specific header in the Global Telecommunications System (GTS) for HRSST buoys, as requested by an Numerical Weather Prediction (NWP) center. It was c...

This paper presents a methodology of iceberg monitoring for Arctic Seas. Indeed, oil/gas operations and seismic surveys are challenging in these areas, when icebergs drifting in the operation areas constitute major hazards. The proposed Icebergs Monitoring Service is based on spaceborne radar technologies for iceberg detection, numerical modeling...

As GODAE ocean forecast systems progress, their contributions toward improving the safety and efficiency of operations at sea will increase. In this article, we review present uses of GODAE ocean forecast systems for various safety applications at sea, including search and rescue drift calculations, iceberg drift calculations, ice cover prediction,...

This paper describes the complementary application of in-situ and remote measurement of ocean currents to deliver solutions to the offshore industry. The critical requirement for calibration of satellite altimeter derived geostrophic currents is explained, along with the benefits of putting short term in-situ data into the longer term context. The...

With more than four years of altimetric measurements over ocean Envisat not only ensures the continuity of the observations provided by ERS -1 and ERS-2, but significantly improves the data quality. The quality assessment of these data is routinely performed at the CLS Space Oceanography Division in the frame of the CNES Segment Sol Altimétrie et O...

During the 1990s, a large number of new tidal atlases were developed, primarily to provide accurate tidal corrections for satellite altimetry applications. During this decade, the French tidal group (FTG), led by C. Le Provost, produced a series of finite element solutions (FES) tidal atlases, among which FES2004 is the latest release, computed fro...

Nearly three years of Envisat altimetric observations over ocean are available inGeophysical Data Record (GDR) products. The quality assessment of these data is routinelyperformed at the CLS Space Oceanography Division in the frame of the CNES Segment SolAltimétrie et Orbitographie (SSALTO) and ESA French Processing and Archiving Center(F-PAC) a...

CLS is in charge of the Envisat RA-2 absolute range calibration in the North West Mediterranean Sea. The project consists of two parts: the determination of the instantaneous sea level and the calibration of Envisat RA-2 with in-situ measurements. CLS developed a software to compare remote sensing measurements with in situ data which are not under...

An improved version of the global hydrodynamic tide solutions [finite element solutions (FESs) FES94, FES95.2.1, and FES98] has been developed, implemented, and validated. The new model is based on the resolution of the tidal barotropic equations on a global finité element grid without any open boundary condition, which leads to solutions independe...

An overview of the SSALTO/DUACS operational altimetry system will be given. SSALTO/DUACS is part of the CNES SSALTO multi-mission ground segment. It is providing global, near real-time altimeter data from TOPEX/POSEIDON, ERS-2, GEOSAT Follow On, Jason-1 and ENVISAT data. The processing system will be described. We will illustrate how the processing...

A new version of the FES hydrodynamic finite element tide model combined with a revised data assimilation procedure is now available. The CEFMO hydrodynamic model previously used to obtain the solution FES94.1 was improved and the assimilation method based on the representer approach was revised. A careful selection of in situ tide gauge data from...

A global ocean model has been developed within the context of TOPEX/Poseidon (T/P) on the basis of a finite element hydrodynamic modeling approach combined with data assimilation based on the representer method. The solution produced at global scale represents a spectacular improvement over what was available before the era of T/P. Typically, the m...