CLS has been involved since 1991 in the quality and performance assessment of altimeter data. Initialized for Topex/Poseidon and ERS-1 missions, these Calibration and Validation of altimeter data activities for altimetry systems are now as crucial as data production. Verification tasks are now routinely carried out at CLS for ERS, Topex/Poseidon, Jason-1 and ENVISAT.

CLS tasks:

• Altimeter data Quality assessement
  Before distribution to users, Jason-1, ENVISAT, T/P and ERS-2 altimeter products data are systematically verified in order to ensure data quality. Analyses are performed on off line products and address all relevant issues about altimeter data. A quality assessment report is then produced and disseminated to users in conjunction with the products.
   
  
• Altimeter system performance monitoring
  Verification activities allow the estimation of instrumental precision and geophysical correction quality for the altimeter system performances. These estimations are then monitored over a long time period in order to ensure a high quality level for applications and scientific studies derived from altimetry.
   
  
• Thematic studies on data use
  Altimetry expertise is useful to conduct thematic studies that help to better understand oceanic signals, which is the main objective of altimetry missions.

Institutions:

These activities are performed for spatial agencies and institutions in charge of altimeter data production CNES (T/P, Jason-1, ENVISAT), ESA (ERS, ENVISAT), IFREMER (ERS)

Users:

More:

• TOPEX/Poseidon and Jason-1, AVISO web site: http://www.jason.oceanobs.com/html/donnees/calval/welcome_uk.html
• ENVISAT, ESA web site: http://envisat.esa.int/calval/
• ERS, Ifremer web site: http://www.ifremer.fr/cersat/en/documentation/references/oprmon.htm