'''Short description:'''

Altimeter satellite gridded Sea Level Anomalies (SLA) computed with respect to a twenty-year [1993, 2012] mean. The SLA is estimated by Optimal Interpolation, merging the measurement from the different altimeter missions available (see QUID document or http://duacs.cls.fr [http://duacs.cls.fr] pages for processing details). The product gives additional variables (i.e. Absolute Dynamic Topography and geostrophic currents (absolute and anomalies)).

This product is processed by the DUACS multimission altimeter data processing system. It serves in near-real time the main operational oceanography and climate forecasting centers in Europe and worldwide. It processes data from all altimeter missions: Jason-3, Sentinel-3A, HY-2A, Saral/AltiKa, Cryosat-2, Jason-2, Jason-1, T/P, ENVISAT, GFO, ERS1/2. It provides a consistent and homogeneous catalogue of products for varied applications, both for near real time applications and offline studies.

To produce maps of Sea Level Anomalies (SLA) and Absolute Dynamic Topography (ADT) in near-real-time, the system uses the along-track altimeter missions from products called SEALEVEL*_PHY_L3_NRT_OBSERVATIONS_008_*. Finally an Optimal Interpolation is made merging all the flying satellites in order to compute gridded SLA and ADT. The geostrophic currents are derived from sla (geostrophic velocities anomalies, ugosa and vgosa variables) and from adt (absolute geostrophic velicities, ugos and vgos variables). Note that the gridded products can be visualized on the LAS (Live Access Data) Aviso+ web page (http://www.aviso.altimetry.fr/en/data/data-access/las-live-access-server.html [http://www.aviso.altimetry.fr/en/data/data-access/las-live-access-server.html]).