Duacs 2021 Climatology Delayed-Time reprocessing
In January 2022, a new version of the SSALTO/Duacs Climatology products distributed by Aviso, so-called Climatology DUACS 2021, has been released with several significant upgrades. A complete reprocessing of the whole L4 altimeter delayed time series has been performed.
Duacs 2021 FSLE Delayed-Time reprocessing
In January 2022, a new version of the SSALTO/Duacs delayed time Finite Size Lyapunov Exponents (FSLEs) products distributed by Aviso, so-called FSLE DUACS 2021, has been released with several significant upgrades. A complete reprocessing of the whole FSLEs delayed time series has been performed.
Upgrades are the following :
-MADT_UV input data are derived from DUACS-DT 2021 instead of DUACS-DT 2018
-Data availability has been extended to December 2020 31th
Data format remains unchanged and is NetCDF-4 Classic with CF standards.
DUACS 2018 Two-sat gridded merged products now disseminated by C3S
The Copernicus Climate Change Service (https://climate.copernicus.eu/) is now in charge of the processing and distribution of the DUACS "two-sat-merged" altimeter sea level gridded products as they are produced on an operational basis for climate oriented applications.
The variables available in the products are the Sea Level Anomaly (SLA), the Absolute Dynamic Topography (ADT) and the associated geostrophic velocities in the Global Ocean, Mediterranean and Black Seas in Delayed-Time. Compared to previous products disseminated by Aviso+, the time series has been fully reprocessed (DUACS DT-2018 standards). Detailed information are available in the product user guide.
You can register here.
Please contact the C3S service desk if needed: climate.copernicus.eu/contact-us
Duacs 2018 FSLE Delayed-Time reprocessing
In July 2018, a new version of the SSALTO/Duacs delayed time Finite Size Lyapunov Exponents (FSLEs) products distributed by Aviso, so-called FSLE DUACS 2018, has been released with several significant upgrades. A complete reprocessing of the whole FSLEs delayed time series has been performed.
Upgrades are the following :
-MADT_UV input data are derived from DUACS-DT 2018 instead of DUACS-DT 2014
-Data are now daily data
-Initial separation is 0.02 degree instead of 0.04 degree
-Data availability has been extended to January 2018 18th
Data format remains unchanged and is NetCDF-4 Classic with CF standards.
Duacs 2018 Climatology Delayed-Time reprocessing
July 2018: Information about DUACS 2018 Climatology products changes and updates
In June 2018, a new version of the SSALTO/Duacs Climatology products distributed by Aviso, so-called Climatology DUACS 2018, has been released with several significant upgrades. A complete reprocessing of the whole L4 altimeter delayed time series has been performed.
The L4 processing parameters impact the L4 Climatology products:
- Higher Sea Level variance over high variability areas (Western boundary currents and circumpolar current for the Global product; Algerian current, Central and Nord Ionian, Ierapetra area for the Mediterranean Sea product)
- Increase of the EKE over high variability areas (Western boundary currents and circumpolar current) and decrease over the equatorial band
- Global reduction of the formal mapping error over the Global ocean; Global augmentation of the formal mapping error for the Mediterranean Sea product.
- Modification of the contribution of the different missions in the L4 products
The positive impact of this new processing on the quality was demonstrated as part of the full reprocessing exercise. Indeed, the assessment of the whole-time series shows a significant improvement of the quality, with notably a better consistency with independent measurements.
Information for Blacksea data
Information for Mediterranean sea data
Duacs 2014 Delayed-Time reprocessing
March 2014: Information about DUACS 2014 products changes and updates
On April 15th, 2014, a new version of the SSALTO/Duacs products distributed by Aviso, so-called DUACS 2014, will be released with several significant upgrades. The whole range of products, in near real time and delayed time, along track and gridded, will be impacted in terms of scientific content, format and naming. A complete reprocessing of the whole altimeter time series has also been performed. These evolutions have strong impacts and will necessitate actions on the user’s side.
These changes contribute to improve the product quality but also to better fit the users’ needs. They mainly concern:
- The change of the reference period: in the DUACS 2014 version, the reference period of the Sea Level Anomalies is based on a 20-year [1993, 2012] period whereas in the former version it is on a 7-year [1993, 1999] period.
- The change of the SLA bias: the general convention to the bias applied to all of the SSALTO/DUACS SLA products consists of having a mean SLA null over the year 1993.
- The evolution of the gridded product resolution and formats: a new Cartesian ¼° resolution is used instead of the 1/3° Mercator grid and a new NetCDF format with new variables is used.
- The evolution of the along track products geophysical content: a new processing is applied in terms of filtering and sub-sampling, inducing less smoothing notably at low latitudes and a denser dataset.
- In addition to these 4 main changes, several other scientific upgrades are applied.
IMPORTANT NOTICE: the major upgrades of DUACS 2014 products, which are summarised in the table below, will have a strong impact and will necessitate actions on the user’s side. We encourage all SSALTO/Duacs users to carefully read the technical note which describes and explains these evolutions.
To insure a smooth transition between the current products and the DUACS 2014 products:
- samples of DUACS 2014 products are already available in the dedicated operational ftp folders.
- a double ftp dissemination is planned: the two versions of the products will be maintained up to mid June.
The ftp access is already possible with the same personal username/password that you already have. Note that the ftp server has a new name since we changed by Aviso+ website: ftp.aviso.altimetry.fr (the former one: ftp.aviso.oceanobs.com is still working).
For any questions, please contact Aviso User Services: aviso(at)altimetry.fr
| DUACS DT 2010 version no more delivered | DUACS 2014 version from April 15, 2014 onwards | |
|---|---|---|
| Reference period for SLA (grid and along-track) | 7-year period [1993, 1999] | 20-year period [1993, 2012] |
| SLA bias convention | - | Mean SLA null over the year 1993 |
| Spatial grid resolution and projection for the global product | 1/3° Mercator | 1/4° Cartesian with new grid points convention |
| Temporal grid resolution | Daily maps in NRT Weekly maps in DT | Daily maps in NRT and DT |
| Grid definition | Latitude range for global product = [-82,82°N] Longitude range for Mediterranean product= [355,396°E] | Latitude range for Global product= [-89.875,89.875°N] Longitude range for Mediterranean product =[354.0625, 396.9375°E] |
| Grid NetCDF Standard | NetCDF 3 Non CF | NetCDF 3-CF, with new variables and attributes |
| Along track filtering for the Global product | Low pass filtered with a cut-off wavelength between 65km and 250km depending on the latitude | Low pass filtered with a cut-off wavelength of 65km for the whole globe |
| Along track sub-sampling for the global product | 1 point kept over 3 to 7 points depending on the latitude | 1 point kept over 2 points for the whole globe |
| Folders and file naming on ftp.aviso.altimetry.fr server | The Near Real Time and Delayed time product are respectively in the “nrt” and “dt” folders | The Near Real Time and Delayed time product are respectively in the “near-real-time” and “delayed-time” folders and file nomenclature has changed |
Further information:
- Technical Note: A new version of SSALTO/Duacs products available in April 2014
- Newsletter #9 (April 2013): Change of the Ssalto/Duacs reference period (p3)
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