Ocean surface A Spot

Current Altimetry processing baselines

Ocean surface A Spot
Ocean surface A Spot

Timeline and overview of the SRAL/MWR Processing Baselines of Sentinel-3.

Last Updated

02 December 2020

Published on

29 November 2018

 Timeline of the of the SRAL/MWR Processing Baselines of Sentinel-3
Figure 1: Timeline of the of the SRAL/MWR Processing Baselines of Sentinel-3

SRAL/MWR Processing Baselines of Sentinel-3 - Baseline Collection 004

Baseline Collection 004 PB 2.61 PB 2.68 - Marine
IPF versions SRAL L1 (SR-1): 06.17
MWR L1 (MW-1): 06.11
SRAL/MWR L2 (SM-2): 06.18
SRAL L1 (SR-1): 06.18/06.19/06.20*
MWR L1 (MW-1): 06.11
SRAL/MWR L2 (SM-2): 06.50
*Bug fix, no impact on data products
Product Notice L1 PN
User Announcement Major evolution of Sentinel-3 Altimetry products New Sentinel-3 Altimetry Processing Baseline released soon
PB Deployment date (NRT) 21/01/2020 09/07/2020
Dataset (NTC)
(sensing time & server)
Operational NTC
From: 27/12/2019
To: Current
Operational NTC
From: 13/06/2020
To: Current
Manifest file Pass number anomalies were corrected, the the Pass number of the products is correct and limited to 770. Anomalies on the L1 manifest have been fixed:
  • The information related to the granule number and position (FIRST/LAST) in the L1 products is correct.
  • The data gaps are properly reported, inside the sensing window.
Calibration   The L1 AUTOCAL sequence was updated and the expected impact on L2 products is low (see below).
Retrackers Update of fitting routine, to correct SWH issue (see below), small impact on retracked parameters.  
SSHA SSHA is now computed using the filtered ionospheric correction, both in SAR and PLRM.
The SSHA PLRM is now computed using PLRM SSB (bug fix)
Improved filtered ionospheric correction used in the SSHA in very small NRT products.
MSS Update of Mean Sea Surface (MSS) to DTU18  
Tide Models Update of FES2014 Tide Model library to the latest version of the library  
Wet tropo Update of radiometer derived Wet Tropo mostly due to updated MWR Antenna Patterns, larger effect getting closer to the coast  
Dry tropo    
Wind Speed/Backscatter coefficient Improved Wind Model for very low/high wind speeds A slight difference on the sigma 0 (below 0.1 dB) and wind speed (below 0.2 m/s) is expected, due to the updated L1 AUTOCAL.
SWH Correction of a software issue for 20-Hz SWH  
Sea Ice   Improvement of the Sea-Ice concentration close to the coastline; no more spuriously low values very close to the cost.
New parameters Filtered Ionospheric correction (iono_cor_alt_filtered_01_ku and iono_cor_alt_01_filtered_plrm_ku) L1A new format: Considering that CAL1 and CAL2 do not change rapidly and are therefore do not need to be repeated for each measurement in the L1A products, the time dimension (time_l1a_echo_sar_ku) and the index (ltm_max_ind) of the following variables has been removed:
  • gprw_meas_ku_l1a_echo_sar_ku
  • gprw_meas_c_l1a_echo_sar_ku
  • burst_power_cor_ku_l1a_echo_sar_ku
  • burst_phase_cor_ku_l1a_echo_sar_ku
Other fixes or changes in the PBs
  • Update of the Characterisation of Sentinel-3 SRAL/MWR instruments
  • SRAL Antenna Aperture 3dB and Internal Path delays
  • MWR Antenna Patterns
  • Correction of Anomalies
  • The L1 products (SR_1_SRA___, SR_1_SRA_A_, SR_1_SRA_BS) will be generated with a different chunk size at netcdf level that should significantly improve the reading speed, but has the side effect of enlarging the product size.
  • An updated Marine Land Mask (SR_2_MLM_AX version 004) is used for the generation of the L2 Marine products: minor changes in the geographical coverage of the Marine L2 products, only related to the extension of the coverage from coastline to Land; from 10 km to 25 km. The extension also applies to the big inland water bodies already included in the Marine L2 products.
Changes to Ground Segment or Spacecraft 28/05/2019: The KREMS safe zone* for both S3A and S3B has been reduced from 300 km radius (around the KREMS radar facility) to 100 km radius.
*zone of the globe where the radiometer (MWR) is disabled and, thus, there is no wet tropospheric correction available from the radiometer, causing the SSHA to be set to a default value.
Since 18/06/2020 a new OLTC is used on board of S3B. The updates are mostly relevant for land users.

For a complete list of changes, please consult the product notices listed above.

For the historical summary table, see Past processing baselines.