Processor Releases

The Envisat GDR and SGDR data were generated using two software: the ESA IPF, from Level0 to Level1B, and the CNES Bibli ALTI, from Level1B to Level2. Moreover a dedicated RAIES (Radar Altimeter Individual EchoeS) L1B processor were developed for processing the individual echoes. The results were appended to the SGDR products, including the power and phase individual waveforms, power scaling factor, tracker range, geolocation, altitude, time tagging.


  Envisat V2.1(+) Envisat V3 
Range Historical L1b (+PTR drift correction Including PTR and L1b updates 
Orbit GDR-C (GDR-D) GDR-E (GDR-D if DORIS is missing) 
Sea State Bias SSB V2.1 SSB V3 
Ionosphere Lanczos filtering for cycle<64, GIM after Iterative filtering for cycle<64, GIM after 
Wet troposphere MWR V2.1 (V2.1+) MWR 5 params solution 
Dry Troposphere  ECMWF Gaussian grid based  ECMWF Gaussian grid based 
Combined Atmospheric Correction MOG2D High Resolution  MOG2D High Resolution 
Ocean Tide  FES GOT 4V8 FES 2014B 
Solid Earth Tide Elastic response to tidal potential  Elastic response to tidal potential 
Pole Tide WAHR85  WAHR85 

A more detailed list of the improvements in reprocessing baseline 3.0 are shortly reported below, further details can be found in the product handbook:

RA2 Level 1 processor 
New independent CAL1 (PTR) Time delay & Power corrections calibration processing chain. After EOM scenario approach 
New independent IF-mask processing chain. After EOM scenario approach 
New independent ICU (Envisat platform clock) & USO (RA2 range clock) smoothing strategy. After EOM scenario approach 
Updated main L1B Measurement Chain, in agreement with the new calibration approach 
Generated Calibration files for each of the Calibration Chains (PTR, USO, IF-mask) for the whole mission 
New generated Auxiliary Characterisation files 
Update of the RAIEs Individual Processor to the last L1B processing version 
Generated RAIES NetCDF files to be appended to the L2 enhanced products 

MWR Level 1b processor 
Updated in-flight calibration insuring consistency between the L2 retrieval algorithms and the RA2-MWR observations 
Updated side lobe correction tables accounting for the actual antenna patterns 

Level 2 processor

  • NetCDF format (standard and enhanced datasets) 
  • Updated Orbit standard: GDR-E 
  • Updated MSS model: CNES CLS 2015 
  • New MSS field, added as a second solution: DTU 15 
  • Updated solution 1 tide model : GOT 4.10c 
  • Updated solution 2 tide model: FES2014b 
  • New long period non equilibrium field: FES2014b 
  • Updated ODLE model: ACE-2 
  • Updated Geoid model: EGM2008 
  • New MDT field: CNES-CLS2013 
  • New dry and wet tropospheric model corrections computed from the integration of ECMWF ERA-Interim profiles at the altitude of the measurement 
  • New barometer height and u/v-component of the wind speed computed from ECMWF ERA-Interim maps 
  • New field for MOG2D High Resolution. Ocean model forced by ECMWF ERA-Interim atmospheric pressures 
  • Updated radiometer wet tropospheric correction: improvement of the retrieval estimation 
  • New radiometer wet tropospheric correction field computed using lapse rate and sea surface temperature as additional input together with the brightness temperatures and the backscatter coefficient 
  • New GPD+ wet tropospheric correction field 
  • Updated backscatter coefficient atmospheric attenuation and alternative computation from model wet tropospheric correction 
  • New SWH modeled instrumental corrections 
  • Updated Sea State Bias derived from 1 year of Envisat altimeter data with version " Baseline v3.0" geophysical models 
  • Updated backscatter to altimeter wind-speed adjustment to account for Envisat reprocessing Baseline V3.0 standard 
  • Updated rain flag and sea ice flag tuning 
  • New sea surface height anomaly fields 
  • New filtered ionospheric correction field issued from CNES SLOOP project (median and Lanczos filtering) 
  • New maneuver flag field 
  • New surface classification and distance to shore fields 
  • New continental ice flag field 
  • New echo and geo corrections fields (LEGOS Ice-2 corrections) 
  • New 2-kHz individual echoes fields (enhanced products only)