Monomission data : updates
See below the latest Monomission products changes and updates.
Before 2020, see the archives of changes in Monomission products.
March 2024: New version 04_00 of L2P products in NTC delay
The new version 04_00 of L2P products in Non-Time-Critical delay (NTC) is available for missions Sentinel-3A/B, Sentinel-6 MF, Jason-3/2/1, SARAL/AltiKa, Cryosat-2, HaiYang-2A/B, TOPEX/Poseidon, Envisat, ERS-1/2, Geosat Follow On. L2P products are netcdf homogenous along-track mono-mission inter-calibrated products, providing as much as possible the same updated corrections and models for all processed missions, in order to facilitate inter-mission comparisons.
The new version 04_00 is disseminated by AVISO+ via FTP/SFTP and TDS (connect to MY AVISO+) for all missions and also on EUMETSAT Data center for Sentinel-6 MF mission.
If you are not yet registered on AVISO+, please connect via the registration form and sign the License Agreement.
Note about the dissemination:
All the data have been delivered in version 04_00. For on going missions, the version 03_00 delivery is stopped, the next cycles will be produced in version 04_00 only.
What is new for this version:
- Homogenous, thoroughly assessed, updated corrections and models; see
- C. Kocha et al. 2023: 30 years of sea level anomaly reprocessed to improve climate and mesoscale satellite data record. DOI 10.24400/527896/a03-2023.3804 , OSTST 2023 meeting.,
- Kocha et al. 2023: Latest update of sea level rise: 30 years of multi-mission datasets EUMETSAT 2023 conference.,
- Lievin et al. 2023. Assessment of reprocessed L2P sea level anomaly products with DT2024 standards (focus on Sentinel-3). S3VT 2023 meeting.
- The list of 2024 standards is given in the file standards_2024.png
Continuous L2P time-series:
- The whole altimetry L2P time-series was reprocessed during 2023
- The reprocessed L2P products are based on recently reprocessed L2 data for several missions (Poseidon/topex GdrF, Sentinel-3 A & Sentinel-3 B Baseline Collection 005, Sentinel-6 A F08, Jason 3 GdrF)
- The reprocessed dataset is disseminated by AVISO+, as detailed above.
For more detailed information please refer to the product page.
November 2023: Release of Reprocessed TOPEX/Poseidon Data
All information in the news.
December 2022: Addition of Sentinel-6A Michael Freilich in NTC L2P SLA products
See details on Product Page
November 2022: New Jason-3 Calibration for L2P Wave products (NRT)
See details here.
October 2022: Version 03_01 of S3B L2P products in Non-Time-Critical delay
An anomaly on the GMSL of Sentinel-3B was observed and it was linked to a reading problem in L1 processor of the USO sign. It impacted the full time-series of S3B data.
Since the installation of L2 Sentinel-3 BC005 version in July 2022, the USO sign is now correct in the Sentinel-3B L2 operational product.
The upcoming L2/L2P S3B NTC reprocessing will fix this anomaly for the whole S3B period. In the meantime, in S3B L2P NTC version V3.01 this sign anomaly has been empirically corrected for the period based on L2 BC004 version (cycles 9 to 67 pass 110 ) following process recommended by EUMESAT :
bias on sla is : range_ocean_01_ku * (1 – uso_corr_freq)
where uso_corr_freq is available on EUMETSAT FTP : ftp://ftp.eumetsat.int/pub/EUM/out/RSP/lucasb/S3B.USO/S3B.cor_uso_freq.daily.csv
(may be not supported by all the browsers)
With version v3.01 of L2P S3B NTC, the L2P BC004 dataset becomes coherent with the new BC005 (regarding the USO sign) and with the GMSL of other missions.
Be careful, in the L2P S3B NTC V3.01 product the variable sea_level_anomaly is corrected but not the range variable. Correction of the USO is included in the variable inter_mission_bias .
This new version is available on AVISO ftp :
/uncross-calibrated/open-ocean/non-time-critical/l2p/sla/s3b/version_03_01
The previous version (/uncross-calibrated/open-ocean/non-time-critical/l2p/sla/s3b/version_03_00) will not be continued.
December 2020: new version 03_00 of L2P products in Non-Time-Critical delay (NTC)
The new version 03_00 of L2P products in Non-Time-Critical delay (NTC) is now available for missions Sentinel-3A/B, Jason-3/2/1, SARAL/AltiKa, Cryosat-2, HaiYang-2A, TOPEX/Poseidon, Envisat, ERS-1/2, Geosat Follow On. L2P products are netcdf homogenous along-track mono-mission products, providing as much as possible the same updated corrections and models for all processed missions, in order to facilitate inter-mission comparisons.
The new version 03_00 is disseminated by AVISO+ via FTP (connect to MY AVISO+)
If you are not yet registered, please connect via the registration form and sign the License Agreement.
Note about the dissemination:
All the data have been delivered in version 03_00. For on going missions, the version 02_00 delivery is stopped, the next cycles will be produced in version 03_00 only.
What is new for this version:
- The whole altimetry L2P time-series was reprocessed during 2020
- Available in netcdf 4 format
- The reprocessed L2P products are based on recently reprocessed L2 data for several missions (ENVISAT V3.0, Sentinel-3 A & Sentinel-3 B Baseline Collection 004, SARAL GdrF, Cryosat Ocean Baseline C)
- Use of WGS84 Reference instead of Topex Ellipsoid
- Homogenous, thoroughly assessed, updated corrections and models (see [Lievin , M., C. Kocha, B. Courcol, S. Philipps, I. Denis, T. Guinle, C. Nogueira Loddo, G. Dibarboure, N. Picot, F. Bignalet Cazalet, 2020: REPROCESSING of SEA LEVEL L2P products for 28 years of altimetry missions. OSTST 2020 virtual meeting.])
For more detailed information please refer to the product page.
March 2020 : SARAL cycle 135 GDR processed with F-standard
SARAL cycle 135 GDR (from 2019-11-11 to 2019-12-16) has just been released.
This is the first GDR cycle processed with F-standard
GDR-F Standard:
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The GDR-F includes about 50 improvements, including New Radiometer processing algorithms, Updated altimeter calibration schemes, Updated geophysical corrections, 3-Parameter SSB… The full differences between Saral GDR-F and GDR-T are described in the SARAL/ALTIKA GDR-F USER GUIDE
Please note that some format differences have to be taken into consideration for readers compatibility :
- The NetCDF-4/HDF5 classic model format with native compression nc_def_var_deflate is used instead of the NetCDF-3 format used so far.
- Three variable names change :
- The mean_sea_surface field has been replaced by mean_sea_surface_sol1
- The interp_flag_mean_sea_surface field has been replaced by interp_flag_mean_sea_surface _sol1
- In Reduced Products, the ocean_tide_sol1 field has been replaced by ocean_tide_sol2
- There is a small bias between the GDR-F SSHA and the GDR-T SSHA : because of GDR-F improvements (mostly Wet Tropospheric Correction, Sea State Bias and Mean Sea Surface), there is a 2.5 cm mean SSHA change wrt cycle 134 (users can refer to SARAL/ALTIKA GDR-F USER GUIDE)
Cycle 135 Calval:
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Please note that this cycle is affected by platform mispointing events. These events are relatively rare and recurring on SARAL since February 2019. During mispointing events, AltiKa has a slightly different behavior which is not related to GDR-F standards.
To illustrate, some passes have a large number of missing measurements. Two passes suffer more than 10% of missing data (pass number 572 and 537). The global percentage of missing measurements (latitude < 50 deg, bathy < -1000m) on this cycle remains very small (0.12%, as opposed to 0.06% or 0.08%). Some passes have a significant number of default value (DV) in the altimeter waveform derived parameters (e.g Backscatter coefficient) : 14 passes include more than 15% of default values over Ocean. Full calval analysis is available in the Saral GDR
Quality Assessment Report
Users are also advised to use only data with off_nadir_angle < 0.09deg² to ensure that the SSHA coverage and quality is almost nominal.
As usual, please feel free to report any findings you might have on GDR-F upgrades and SARAL data in general.
January 2020: SARAL/AltiKa : new GDR-F products standard
Following OSTST recommendations, we are really happy to provide to Altimetry community the release of the SARAL/AltiKa new GDR-F products standard.
The delivery is planned as follows:
| AltiKa Product | IGDR | GDR |
|---|---|---|
| Content | Geophysics data | Geophysics data |
| Validation | Dissemination after partial validation | Dissemination after exhaustive validation |
| Retracking | Applied | Applied |
| Orbit type | MOE-F | POE-F |
| Cycle | From cycle 137 (first data 20-Jan-2020) | From cycle 135 (first data 11-Nov-2019) |
The full reprocessing delivery till cycle 134 included is planned in May 2020.
It is planned to upgrade the OGDRs during week 5.
Please note the following variable names changes :
• mean_sea_surface is no longer available, replaced by mean_sea_surface_sol1
• interp_flag_mean_sea_surface is no longer available, replaced by interp_flag_mean_sea_surface_sol1
• In Reduced Products Only, ocean_tide_sol1 is no longer available, replaced by ocean_tide_sol2
The related documentation (cf SARAL user Product) is available here
The major improvements are the following:
| New fields | Updated fields |
|---|---|
| 3-Parameter SSB (SWH, wind and swell) | Retracking accounting for the actual altimeter antenna aperture |
| Wet & dry tropospheric correction based on 3D ECMWF fields | Updated altimeter calibration schemes (CAL2 normalization, CAL1 not corrected by CAL2, updated gains values) |
| Atmospheric correction derived from ECMWF fields | New Radiometer processing algorithms |
New geophysical corrections: | Updated geophysical corrections: FES2014 & GOT4.10 ocean tide models S. Desai pole tide with new IERS linear mean pole 2018 Mean Dynamic Topography model EGM 2008 geoid model |
| Platform mispointing angles | Netcdf v4 product format |
The details and comparisons between the versions can be found here.
DISSEMINATION:
The files will be available on ftp in the folders igdr_f, sigdr_f and ssha_igdr_f.
Your feedback on this new standard is welcome
For any question, please contact the AVISO helpdesk (aviso@altimetry.fr).
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