Duacs is the Ssalto multimission altimeter data processing system. It serves in near-real time the main operational oceanography and climate forecasting centers in Europe and worldwide.

Ssalto/Duacs system processes data from all altimeter missions (Jason-1&2, T/P, Envisat, GFO, ERS-1 & 2 and even Geosat) to provide a consistent and homogeneous catalogue of products for varied applications, both for near real time applications and offline studies. Ssalto/Duacs Near-Real Time data are used, in particular, by Godae and its French contribution Mercator Océan. In delayed time, hundreds of teams retrieve historical Duacs datasets.

Latest Duacs maps (Sea Level Anomalies, top, Absolute Dynamic Topography, bottom). Browse through more of them through our "Sea views" interface

Some data files released during the last Ssalto/Duacs Delayed-Time temporal extension (see December 2011: Temporal extension up to July 2011 of Ssalto/Duacs delayed time (DT) products below) appeared to be erroneous and are now corrected.
Indeed, the coordinates grid (lon/lat) was not well defined and may cause an erroneous reading with some softwares (whereas others sofwares are not impacted).

If you have already downloaded the files for the data period between 2011/01/12 and 2011/07/06 (or in other words for all the production date of 2011/12/08), please check them with the softwares you use: Delayed-Time, updated and reference series for Global area in Maps of Sea Level Anomalies for the height and formal mapping error variables, with a weekly resolution (the MSLA with a 1/4° and 1° spatial resolution, respectively the filenames with *msla_h_qd* and *msla_h_lr*; and the geostrophic velocities UV are not concerned). In details, the following folders and files were impacted: 

• /global/dt/ref/msla/merged/h/, data files between
  • dt_ref_global_merged_msla_h_20110112_20110112_20111208.nc.gz and
  • dt_ref_global_merged_msla_h_20110706_20110706_20111208.nc.gz
• /global/dt/ref/msla/merged/err/, data files between
  
  • dt_ref_global_merged_msla_err_20110112_20110112_20111208.nc.gz and
  • dt_ref_global_merged_msla_err_20110706_20110706_20111208.nc.gz
• /global/dt/upd/msla/merged/h/, data files between
  
  • dt_upd_global_merged_msla_h_20110112_20110112_20111208.nc.gz and
  • dt_upd_global_merged_msla_h_20110706_20110706_20111208.nc.gz
• /global/dt/upd/msla/merged/err, data files between
  
  • dt_upd_global_merged_msla_err_20110112_20110112_20111208.nc.gz and
  • dt_upd_global_merged_msla_err_20110706_20110706_20111208.nc.gz

If you have encountered some difficulties to plot these last files, we invite you to download again the new corrected files that the production date is 2012/01/16 (which is the third date in each filename), on the authenticated data access services.

Since October 2011, the Ssalto/Duacs Delayed-Time MSLA and MADT were integrated through the Opendap with the daily resolution (by default, the weekly resolution was also included in this dataset).

In order to integrate to the Opendap and the Extraction Tool, the latest DT extension made on the ftp server for weekly products (extension up to July 2011), a new dataset is created to offer at once the weekly and the daily resolutions. The daily resolution is integrated in a new dataset whereas the old dataset contains only the weekly resolution  (see table below for the detailed filenames).
The temporal extension of these two datasets are different since the daily resolution was made as an experimental and temporary production and therefore, it is not upgraded at each Delayed-Time extension: 

Finally, an upgrade on the Extraction Tool enables to offer a new service. On each last page where you can download the data (after you have defined your own dataset), a new "script" button allows you to access on Python script command lines that matches the current extraction. These command lines help you to make your own script from the shell of you system (Linux/Unix/window).

Further information:

• Data access services: Authenticated Opendap and Extraction Tool
• If you are not registered and want to access those services (NB. for scientifc uses only), we request you to fill in the online form: http://www.aviso.oceanobs.com/en/data/registration-form/

Two new Duacs regional products are released on Wednesday, 11th January 2012: Arctic Ocean and Europe area, for addressing the needs of data assimilation and validation in regional models.
Those new products include Along-track multimission Sea Level Anomalies data in Near-Real Time.
They are delivered via authenticated FTP (see Access to Ssalto/Duacs products). If you already have an FTP account, your access is automatically updated; this means that no new subscription is required.
The data are in the following folders: regional-arctic/ and regional-europe/ .
The Geographic coverage includes:

• for Arctic area, an enlarged Arctic Ocean : 45°N-82°N / 0°-360°E
• for Europe area: 21°N-66°N / -25°W-42°E (Iberic-Biscaye-Ireland and Northwest shelves areas ; Baltic, Mediterranean and Black Seas).

Following the initiative launched by TAPAS (Tailored Altimeter Product for Assimilation Systems) in the MyOcean project with all the Modeling and Forecasting Centers (MFCs), the Europe regional products has been processed with adapted filtering and resolution. Those parameters as well as the coverage have been tuned in order to provide boundary conditions for the Atlantic assimilation models.
Indeed, the Europe area includes, among others, the Mediterranean and Black Seas which already belong to dedicated regional products (in regional-mfstep and regional-blacksea folders). However, note that if you need to study the Mediterranean or the Black Sea, you'd better use the dedicated regional products since the processing parameters have been fitted to be adapted to the dynamics of the ocean in those regions, which is not the case for the Europe product.
Nomenclature, temporal availability, product generation or corrections applied can be retrieved in the Ssalto/Duacs User Handbook.