Initiated in 1997, the near-real time (NRT) processing of altimeter data was developed and operated by CLS as part of Duacs (Developing Use of Altimetry for Climate Studies). Duacs started as an European Commission Project (Duacs), funded under the European Commission and the Midi-Pyrénées regional council.
A new version of the system (Ssalto/Duacs) was developed in parallel and has been operational since March 2002 in order to serve operational oceanography and climate forecasting projects. This project is the CNES Ssalto multi-mission altimeter data processing with funding from CNES and the Midi-Pyrénées regional council. Duacs is used to serve operational oceanography and climate forecasting projects.
CLS tasks:
- Definition, development and improvements of the near-real time processing algorithm of altimeter data.
- Technical and scientific expertise of the various data used in the processing and of the products Ssalto/Duacs.
- Operation of the Ssalto/Duacs processing performed in CLS:
- Continuous processing acquisition in near-real time of altimetric data from the current altimeter missions (i.e Topex/Poseidon, ERS-2, Geosat Follow On, Jason-1 and Envisat).
- Validation and correction of all altimetric data sets using the state of art of algorithms also used in CalVal project. Using data from altimetric satellites with precise orbital determination and combining data from several satellites enables Duacs to produce in near-real time homogeneous data with an optimal quality.
- Generation in near-real time and twice a week of homogeneous and added value products:
- along-track Sea Level Anomaly data (Near-real Time SLA, called NRT-SLA),
- maps of Sea Level Anomaly (NRT-MSLA) for each satellite mission,
- a global map of sea level anomaly merged from all satellite missions (Merged NRT-MSLA). This high resolution gridded product enables a better mesoscale circulation observation,
- geostrophic currents derived from the altimeter sea level gradient
- Distribution of Ssalto/Duacs products by AVISO User Services (web and ftp).
Users:
Duacs and then Ssalto/Duacs projects have demonstrated that altimeter data can be processed in near-real time with sufficient quality requirements to serve operational oceanography (MERCATOR, MERSEA and GODAE projects), from mesoscale to climate applications and to improve seasonal climate forecasts (MFSTEP and ENACT projects). CLS remains in charge of the commercial applications of these near-real time products (EMOFOR project for offshore and CATSAT project for fisheries).
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