You will find the details in the handbook 

These products are processed by the Sentinel-3 L2P/L3 Marine Altimetry Service (CNES/CLS), in the frame of a EUMETSAT contract, funded by the European Union. 

The new version 02_00 is disseminated by AVISO+ via ftp or AVISO+ CNES Data Center (see the product sheet). Note that the last cycle produced in version 01_00 has already been delivered (cycle 22). The next cycle 23 will be produced only in version 02_00. 

With this new version:

• the input data are the “spring 2017 reprocessed” version of input NTC L2 products fully detailed in the EUMETSAT S3A STM reprocessing technical note
• the standards are the same as in 01_00 version
• new cycles are available (cycles 5 to 11)

Upgrade of Delayed-Time CORSSH data including new standards (standards 2018) now called L2P products (for Level-2+). The format is adapted to the existing Sentinel-3A L2P products already delivered on AVISO+ (NetCDF format with change in the variables names). All information is described in the product page and in the <link file:23163 - download>handbook</link>.

The information about the dissemination for L2P all missions except for S3A is detailed in the table below: 

Note about Wind/Wave variables:
The variables swh and sigma0 don't exist anymore in the L2P products. You will find those variables in the L2 products (GDR/IGDR/OGDR) on the AVISO+ dedicated web page product. 

The new GDR-E orbit standard becomes operational on May 26th, 2015! It is or will be used in all altimeter processing chains in coming weeks or months.

Foreseen Improvements

The main changes between the previous GDR-D and the new GDR-E POD standards are (for complete details, please consult the summary of all the changes):

• Geophysical models:
  • Updated geopotential model accounting for interannual variability
  • Orbits better referenced to the center-of-mass of the total Earth system
• Orbit parameterization:
  • Calibrated semi-empirical Solar Radiation Pressure (SRP) models
  • Improved stochastic (reduced-dynamic) parameterization
  • DORIS-only and GPS+DORIS orbits
  • SLR used as a reference to independently evaluate orbit precision and stability

The foreseen improvements are:

• ~2mm RMS radial orbit improvement over the previous GDR-D solutions for Cryosat-2 (based on high elevation SLR residuals)
• better agreement of the geographically correlated radial orbit drift rate (1 mm/y to less than 0.5 mm/y over ~6 years) with respect to JPL (RLSE14A) GPS-only reduced-dynamic orbits for Jason-2

 Jason-2 mission

For Jason-2, the new MOE GDR-E orbits will be released on May 26th, 2015 (made with data of May 25th). Thus, IGDRs products of May 26th 2015 will benefit from the new POD standard. Concerning the precise ephemeris, the new POE GDR-E orbit will be released for cycle 254.

A special interest is paid to Jason-2, which is the reference mission in the multi-mission SSALTO/DUACS system (see the dedicated webpage)

The OSTM/Jason-2 products Handbook has been updated.

Other missions

• For Cryosat-2, the new standard is already operational since April 2nd, 2015 for MOE and during cycle 67 for POE (arc 260). 
• Jason-3 POE orbits will be produced in GDR-E standards from cycle 1.
• Saral orbits will switch to the GDR-E standards on July 2nd (data of July 1st), 2015 for MOE and from cycle 25 for POE.
• Jason-1 POE orbits will be available by the beginning of July 2015.
• HY-2A & ENVISAT POE orbits will switch to the GDR-E standards at a later stage.

For any question, please contact aviso(at)altimetry.fr

We are pleased to provide this short synthesis of the Saral IGDR-T products data quality assessment over oceans. CalVal analysis was performed on Cnes and CLS side during past months using classical tools like Cross-Overs and SLA analysis. 

This memo provides early metrics computed on our side in order to ease the Saral use. This is based on the analysis of IGDR and OGDRs data dated from mid March 2013 to end of June. The Calval analysis will continue with the assessment of the first GDRs cycles and the routine monitoring of OGDRs and IGDRs products.

We also like to mention that a patch has been prepared to correct for some anomalies and to account for the in-flight calibration data in the ground processing. The evolutions included in this patch are described in the pdf document. This patch has been installed on IGDRs products on July 11^th. It will be installed on OGDRs processing chains around July 17^th.

Regarding the IGDRs products, the first product generated with this patch is :
SRL_IPN/R/S_2PTP004_0395_20130710_235618_20130711_004636.Cnes.nc

This is mentioned in the Netcdf product in the global attribute ‘references’. This patch corresponds to the patch number 2 on the Level1B Scientific Library ; number 10 on the Level2 Scientific Library and number 9 on the Processing Pilot chain :
references = "L1 library=V3.1p1p2, L2 library=V4.2p1p6p9p10, Processing Pilot=V3-4-1p2p5p6p7p8p9" ;

Former values were:
references = "L1 library=V3.1p1, L2 library=V4.2p1p6p9, Processing Pilot=V3-4-1p2p5p6p7p8" ;

Amandine Guillot –Saral CalVal Responsible
Nicolas Picot - Saral Measurement System Engineer
On behalf of Cnes Saral project.

Jason-1 is on its new geodetic orbit since May 2012. The cycle 500 is the first cycle of this geodetic mission and the CorSSH products are now delivered. No SLA is delivered after cycle 374 since the orbit is non repetitive.

For Jason-2, monomission CorSSH and SLA are now using the version D of Jason-2 Geophysical Data Records (GDRs) standards starting from cycle 146. Previous cycles are still in version C, and will be reprocessed in the future.

All information available in the CorSSH and SLA user Handbook

Jason-2 OGDRs, IGDRs and GDRs will switch to a new altimetric standard (version "D") this summer. A reprocessing campaign will process the four first years of mission to provide an homogeneous GDR dataset.

Read more

Following the on-board anomaly on March 3rd, the Cnes-Nasa Joint Steering Group directed the Jason-1 Project to move the satellite to a geodetic orbit.

Maneuvers

The target orbit was 12+297/406 with a mean altitude at the Equator of 1323.4 km.
Jason-1 maneuver operations were started on April 23^rd with this baseline, and the first operations to lower the orbit were performed on April 25^th.
After an initial series of 4 maneuvers were completed, they encountered a serious new propulsion anomaly which resulted in the unexpected overconsumption of hydrazine.
A 5^th maneuver was designed in order to correct orbital eccentricity. At the time of this new anomaly, Jason-1 was -12.0 km below the reference altimetric orbit with 600m remaining to reach the -12.6 km goal, however there were very few grams of fuel remaining in the tank to continue orbit lowering.

Final orbit

After checking the current orbit carefully, the operational team determined that a geodetic mission was still possible. It was also decided to preserve all remaining fuel for future station keeping maneuvers which is mandatory in a geodetic orbit. Core payloads were switched ON on May 4^th and after some POSEIDON2 radar (PRF) adjustments the mission was resumed on May 7^th at 15:12:48 UTC.

Below are the characteristics of the new orbit which will be maintained, as before, within +/- 1km control box at the Equator:

Products

For this new phase of the Jason-1 mission, the cycle numbering will restart at 500. Off-line products will be produced once a day for the IGDR and every 11 days for the GDR's.

Since February 2011, the reprocessing of Envisat data in version 2.1 has begun and will continue during all the year 2011. It concerns cycles 10 to 92.

See the validation reports (in pdf)

The changes and comparisons between version 2.1 (IPF V6.04 and CMA V9.3_05) and the previous version (IPF V5.06 and CMA V9.2_03) have been analysed by: Ollivier A, J.F. Legeais, N. Granier, Y. Faugere, F-PAC Calval Team: "CalVal status on the Envisat V2.1 reprocessing impact on main altimetric parameters"

Mofications were applied on CorSSH and SLA monomission products with new standards for corrections and/or models and processing of ERS-1 data. Major changes are:

• T/P: new non parametric Sea State bias solution from N.Tran et al. (2010) with up-to-date standards (e.g. : DAC or wind algorithm) and orbit solution.
• T/P: new orbit solution, kindly provided by GSFC.
• Jason-1: GDR-C used from 2009 reprocessing.
• ENVISAT: new non parametric SSB solution from S.Labroue.
• ENVISAT: GDR-C orbits used (from cycle 15).
• GFO: new orbit solution, kindly provided by GSFC. As the new solution is not allways available, the GDR orbit is also used with empirical coherency restoration in between.
• GFO: new non parametric Sea State bias solution from N. Tran et al. (2010) with up-to-date standards and orbit solution (computed after orbit error minimization on calibrated reference missions)
• ERS: minimization of brightness temperature drift before wet tropo computation (NN)
• All missions: GDR-C or better standards applied whenever necessary (GOT4v7, High Resolution DAC correction...)
• All missions: new mean profiles computed in coherency with the new standards and algorithms. New algorithms were applied to correct for time-averaging period discrepancies (e.g.: T/P = Jason-1) or ocean variability. The new mean profiles are still referenced over 1993-1999 for the sake of coherency, but they integrate a precious information from the most recent missions and datasets.
• All missions: minor upgrades of the editing process and complete re-editing based on new standards and corrections.

The handbook has been updated to follow all changes.

We are changing our ftp site to provide you with a better service. From now on monomission products (SLA monomission and CorSSH) are delivered on a new ftp site.

The new ftp address is: ftp.aviso.oceanobs.com . This one replace the old one (ftp.cls.fr).

The anonymous access, the directory paths and the file nomenclature don't change : ftp://ftp.aviso.oceanobs.com/pub/oceano/AVISO/SSH/monomission/

After more than 7 years of service on the nominal ground track, the Jason-1 satellite began several maneuvers to be moved to a new ground track on January 26, 2009 after the end of repeat cycle 259. Several maneuvers shifted Jason-1 on its new orbit  on mid-February. Nominal production of all data products in the new orbit resumed on 14-Feb-2009 at 20:51 UTC.  Nominal science data delivery will continue for the remainder of Science Cycle 262.  The first complete science cycle in the new Jason-1 orbit (Cycle 263) will begin at 04:18 UTC on 20-Feb-2009.

Jason-1 assumes a new orbit midway between its original ground tracks but with a time lag of approximately 5 days with OSTM/Jason-2.The OSTM/Jason-2 satellite will continue the long term climate data record on the primary Topex/Jason-1/OSTM-Jason-2 ground tracks.  

Jason-1 monomission CorSSH and SLA are now using the new version C Jason-1 Geophysical Data Records (GDRs) standards, starting from cycle 233. Previous cycles are still in version B, and will be reprocessed in the future, following Jason-1 GDRs reprocessing.

New version C Jason-1 Geophysical Data Records (GDRs). Currently, cycles 213-232, and 240 are available on the Aviso and Podaac ftp servers:

• AVISO: ftp://avisoftp.cnes.fr/AVISO/pub/jason-1/gdr_c/ 
• PODAAC: ftp://podaac.jpl.nasa.gov/sea_surface_height/jason/gdr_c/

Early versions of some cycles (e.g. 220-239) of the version C GDRs were released in July, but have since been  reprocessed with modified precise orbit ephemerides. Users are advised to download those cycles again, and to only use version C GDRs that have file generation times of August 12, 2008 onwards.  All version C Jason-1 GDRs for all cycles will be available by the middle of 2009.

Users are advised to note the following primary differences between the version B and version C Jason-1 GDRs:

• Use of ITRF2005 reference frame and time variable gravity in precise orbits. 
• In improved sea state bias model that is consistent with the MLE4 retracked altimeter data.
• Updated altimeter instrument corrections.
• Recalibrated JMR measurements using data from cycles 1-227.

Given the schedule for reprocessing version C GDRs, we are providing users with an interim means to correct the version B Jason-1 GDRs for these primary changes, as follows:

• GDR-C precise orbit ephemerides are provided as sp1 files on the following ftp server.    ftp://avisoftp.cnes.fr/AVISO/pub/jason-1/gdr_c_aux_files/poe/
• The sea state bias model used on the version C GDRs is provided on the following ftp server:    ftp://avisoftp.cnes.fr/AVISO/pub/jason-1/gdr_c_aux_files/
• Tables of the altimeter instrument corrections used on the version C GDRs are provides on the following ftp server:ftp://avisoftp.cnes.fr/AVISO/pub/jason-1/gdr_c_aux_files/ 
• A JMR replacement product that adopts the JMR calibration parameters used to generate the version C GDRs is available on the following ftp server:   ftp://podaac.jpl.nasa.gov/pub/sea_surface_height/jason/jmr_replacement/

An updated user handbook is provided:

• SMM-MU-M5-OP-13184-CN, Edition 4.1, October 2008 
  Aviso and PoDaac User Handbook - IGDR and GDR Jason-1 Products, pdf version (2 Mo)

Mofications were applied on Envisat CorSSH and monomission SLA to follow Jason-1 standards, starting from cycle 65. Changes are:

• Mog2D high resolution replaces Mog2D
• Wet tropospheric correction is now a composite of radiometer correction (further than 50 km from the coast) and model correction (between 10 and 50 km), with smoothing at the frontier.
• change in ERS mean profile, including now coastal effects
• GIM correction replaces the dual-frequency ionospheric correction

The handbook has been updated to follow all changes.

Mofications were applied on CorSSH and monomission SLA to follow Jason-1 GDR-C standards. Changes are:

• Mog2D high resolution replaces Mog2D
• Wet tropospheric correction is now a composite of radiometer correction (further than 50 km from the coast) and model correction (between 10 and 50 km), with smoothing at the frontier.
• changes in validation process (including a new ice flag, effects from Mog2D High Resolution, looser criteria near the coasts...)
• change in T/P mean profile, including now coastal effects

The handbook has been updated to follow all changes.

Jason-1 CorSSH and SLA "Ref" products were reprocessed:

• sea state bias (SSB) is issued from non parametric method already available in the GDRs 'b' from cycle 001 to 021 (Labroue, S., P. Gaspar, J. Dorandeu, F. Mertz, OZ. Zanifé, 2006, Overview of the Improvements Made on the Empirical Determination of the Sea State Bias Correction, 15 years of progress in radar altimetry Symposium, Venice, Italy, 2006)
• a new ice flag, similar as for ERS, is now applied.

Attention: cycles 32, 60, 89, 90 et 91 are not validated yet and not delivered on the server.

Envisat CorSSH and SLA products were reprocessed, modifications are the same as for Jason-1; please refer to previous information published on August 9, 2006.

Jason-1 CorSSH and SLA products were reprocessed, hereafter the modifications:

• Sea State Bias correction is the one provided in the GDRs 'b' and is homogeneous all along the time period.
• With the new version of GDRs (cycle 136) IB correction based on a cartesian grid (cycle 1 to 135) was, by mistake, replaced by an IB correction based.

Implementation of a new Envisat operational production chain; starting dates for the new processing chain are as follows:

• IGDR products (near real time products): October, 24th 2005
• GDR products (off line products): September, 20th 2005 (i.e. from cycle 41).

Improvements concern MOE/POE orbit computation chains and new algorithms.
More details about those improvements are available on ESA web site.

Implementation of a new Jason-1 operational production chain; starting dates for the new processing chain are as follows:

• IGDR products (near real time products): October, 24th 2005 (i.e. first day of cycle 140)
• GDR products (off line products): September, 14th 2005 (i.e. from cycle 136).

This new version will be identified with the letter "b", therefore GDR Jason-1 products will be named "JA1_GDR_2Pb" from the start of the new chain.

Main features:

New MOE and POE orbit computation chains :

Both chains will use the latest GRACE geoid model developed by the LEGOS group (EIGEN-CG03C). The POE chain also takes into account GPS data (MOE orbits are computed with Doris data solely). See Choi et al., 2004.

New JMR characterization file :

A new calibration file has been developed to correct for jumps in the JMR path delays and to minimize yaw state effects (Brown et al., 2004).

New MLE4 retracking algorithm :

Based on a second-order altimeter echo model, MLE4 simultaneously retrieves the 4 parameters that can be inverted from the altimeter waveforms: epoch, SWH, Sigma0 and mispointing angle. This algorithm is more robust for large off-nadir angles, (up to 0.5°, as encountered in August-September 2005). See Amarouche et al. 2004.

Instrumental tables (fields # 31-32, 47-48 and 61-62):

New instrumental correction tables have been established, based on MLE4 algorithm (Thibaut et al., 2004).

Vandemark/Gourrion wind algorithm (fields # 85-88):

A specific empirical wind-speed model has been tailored to Jason-1 data by Collard et al. (2004). This represents an update from the previous version of the altimeter wind estimate (the previous algorithm was fitted on TOPEX data).

SSB table (fields # 38-40):

Sea-State bias table has been recomputed accounting for the impact of the geophysical parameters used (Labroue et al., 2003). Note that this SSB table was derived from altimeter data that we computed from the MLE3 retracking algorithm.

Tidal models (fields # 77-78 and 81-82):

The two tide models (FES and GOT) have been updated to their latest versions (respectively FES2004 and GOT00.2). As before, both geocentric ocean tide fields (fields #77 and #78) also include the load tides from the respective models (also provided separately in fields #81 and #82), and the equilibrium long-period ocean tide (also provided separately in field #79). These two fields (#77 and #78) now also include the S1 oceanic response to atmospheric pressure based on the model from Ray and Egbert (2004). The FES2004 model now also includes the M4 ocean tide. Note that the load tide fields (fields #81 and #82) only include the load tides from the GOT00.2 and FES2004 models, and do not contain the load tides from the S1, M4, or equilibrium long-period ocean tides.

Non Equilibrium Long Period Tides (fields # 80):

Previously set to default value, this field is now calculated based on the predictions of the Mf, Mm, Mtm, Msqm tides from the FES2004 model. This field is provided as a correction to the equilibrium long-period ocean tide. To apply this correction, it should be added to fields 77, 78, or 79, depending on which ocean tide field is being used.

MSS (field # 70):

CLS01 MSS model solution has been implemented (Hernandez, 2002).

Non-tidal High Frequency correction (field # 75) :

The correction is calculated from the Mog2D ocean model, and is only available in GDR products. Note that the IB correction is still taken from ECMWF atmospheric pressure products. This field is provided as a correction to the inverse barometer. To apply this correction, it should be added to field #74.

S1/S2 management (fields # 33 and 74) :

S1 and S2 ocean tide effects have been removed from the inverse barometer correction (field #74) and from the non-tidal high frequency correction (field #75) as both ocean tides are now included in the ocean tide models. Note also that explicit models for the S1 and S2 atmospheric tides have been added into the dry tropospheric correction.

Rain Flag (field # 93):

A new table provided by Tournadre (2004) is used in ground processing for rain_flag determination.