Gridded Sea Level Heights and derived variables

Types of dataset: Ssalto/Duacs gridded multimission altimeter products. 

Contents: gridded multimission sea surface heights computed with respect to a twenty-year mean. Several variables are proposed: Sea Level Anomaly, Absolute Dynamic Topography, Geostrophic Velocities. Several timeliness: near-real-time and delayed-time.

Condition of access : The processing and distribution of the Sea Level Anomaly (SLA-H), Absolute Dynamic Topography (ADT-H)  Heights and Geostrophic Velocities (SLA-UV and ADT-UV) products are made by:

• The Copernicus Marine Environment Monitoring Service (CMEMS) for the near-real-time and the delayed-time "allsat" products (formerly distributed by Aviso+, no change in the scientific content). Those products are viewable on the AVISO+ Live Access Server (LAS).
• The Copernicus Climate Change Service (C3S) for the delayed-time "twosat" product (formerly distributed by Aviso+, no change in the scientific content). Note that they are also distributed by CMEMS as described below.

Description: gridded multimission product, provided in near-real time and in delayed time. In delayed-time, there are two series available: the "allsat" series and the "twosat" series. In near-real-time, only the "allsat" series is distributed.

• The near-real-time product is available during a few months at most, from the latest update of the delayed-time product to today. It is disseminated by CMEMS: see the details in the document Migration AVISO+ to CMEMS and AVISO+ to C3S (section3).
• The delayed-time "allsat" product is the time serie of the merged maps computed with all the satellites available at a given time. It begins in 1993 and provide the maps with the best mapping as possible but not homogeneous in time. It is disseminated by CMEMS: see the details in the document Migration AVISO+ to CMEMS and AVISO+ to C3S (section4).
• The delayed-time "twosat" product is the time serie of the merged maps computed with a maximum of two satellites at a given time. It begins in 1993 and provide the maps homogeneous in time thanks to a stable sampling but might not be the best in quality at a given time. It is useful for the climate studies for example which need stable product in time. It is disseminated by C3S and CMEMS: see the details in the document Migration AVISO+ to CMEMS and AVISO+ to C3S (section5).

The informations about the satellites taken into account are given in the NetCDF file global attributes description (named "platform").

Geographic coverage: global. A specific regional product with an improved quality is available in local areas.

Copyright: 
1993 - ongoing EU Copernicus Marine Service for near-real-time product and delayed-time "allsat" product.
1993 - ongoing Copernicus Climate Change and Atmosphere Monitoring Services for delayed-time "twosat" product. Useful links to CMEMS and C3S in the document: Migration AVISO+ to CMEMS and AVISO+ to C3S.

See also: DUACS Product validation & information