About CERSAT

Background

Created in 1991, the CERSAT  (Centre ERS d'Archivage et de Traitement - French ERS Processing and Archiving Facility) is part of the ESA (European Space Agency) ground segment for the ERS-1 and ERS-2 Earth observation satellites. This computing center is managed by the engineering team of the Department of Oceanography from Space at IFREMER (Institut Français de Recherche pour l'Exploitation de la mer), Plouzané (France). In line with the contract between ESA and IFREMER, CERSAT performs off-line processing of data from the ERS-1 and ERS-2 "low-bit rate" sensors : Radar Altimeter, Scatterometer, Micro-wave sounder and SAR in wave mode. These data, available either on CDROM, exabyte or through this web site, are distributed to the scientific community world-wide.

Since 1996, the CERSAT has diversified its activities, handling new datasets from various sensors similar or complementary to those of ERS (SSM/I, ADEOS/NSCAT, QuikSCAT/SeaWinds), and generating new value-added products from its growing database : mean wind fields, sea-ice characterization maps or multi-sensor colocated datasets (combining ERS, NSCAT, QuikSCAT/SeaWinds, TOPEX, SSM/I, JASON-1, ENVISAT satellites but also buoys and model outputs). As the ERS mission is about to end, CERSAT has been evolving for a few years towards a multi-mission centre for archiving, processing and validating multi-sensor data for oceanography, including upcoming missions like ADEOS II/SeaWinds (2001) or METOP/ASCAT (2003), to create homogeneous series of value-added data like wind fields, fluxes, waves or sea-ice.

The operational center is operated by a technical team of  five sub-contractors, whereas the CERSAT engineers monitor the data processing, ensuring quality control, interfaces with the different entities of the ERS ground segment or with other collaborating data centers, as well as maintenance or improvement of the operating system.

The main background activities include :

• the archiving and distribution of the sensor data of various ocean obervation satellite, including -as a member of ESA ground segment- the radar altimeter (RA), the micro-wave sounder (ATSR/MW) and scatterometer data of ERS-1 & ERS-2, and -as a mirror site of JPL/PO-DAAC- scatterometer data of ADEOS/NSCAT and QuikSCAT, but also Special Sensor Microwave Imager (SSM/I) data, etc...
• the processing of  raw sensor data toward geophysical values, such as wind vectors from the ERS scatteromer, sea-level related parameters from ERS radar altimeter ,...
• the generation of value-added products such as mean wind fields, polar sea ice grids, colocated multi-sensor datasets
• the distribution of all these products to the ocenographic community

Scientific expertise

Thanks to its knowledge in physical measurements, the scientific team of the Département d'Océanographie Spatiale ensures:

• the quality control of the generated products, monitoring the quality of the retrieved geophysical quantities (to detect potential instrumental effects) and tracking possible sensor drifts or malfunction.
• the improvement of algorithms used to estimate geophysical parameters from instrumental data.
• the development of value-added products (global gridded fields, sea-ice maps, colocated datasets from various satellite sensors,...).

Data distribution

The products generated by the CERSAT are distributed free of charge to scientists :

• on-line, through CERSAT ftp and web sites, enabling data subsetting and extraction according to temporal and geographical criteria.
• on various storage media, such as DVD, CD-ROM or exabyte for some products (delivered to more than 2000 users in the world).

The CERSAT also presents and makes its products known to the oceanographic community through international meetings and workshops.

Projects and applications

The CERSAT and the scientific team of the Département d'Océanographie Spatiale are involved in other projects, studies and experients using these products. All the "life cycle" of the data is thus covered, from raw processing to applications in oceanographical studies, such as ocean circulation model forcing, sea-ice observation, tracking of cyclonic phenomena,...

More information on CERSAT Web site.