Major upgrade of Sentinel-3 Altimetry products

Sentinel-3 SRAL (dual-frequency Synthetic Aperture Radar Altimeter) Level 1 and Level 2 products will be enhanced on 13 December.

Thursday, 14 December 2017

Major upgrade of Sentinel-3 Altimetry products

A major evolution of the Sentinel-3 Altimetry products has been performed, increasing the baseline collection of the products from version 002 to 003.

Some of the changes are:

  • An updated version of the SAMOSA retracking algorithm (now following DPM 2.5)
  • An updated Mean Sea Surfaces (DTU 15 [default] and CNES/CLS 15)
  • An updated tide model (FES 2014 [default] and GOT 4.10)

This evolution is expected to improve the consistency of SAR and PLRM retrievals for sea surface height and to be even more in line with the ECMWF models for winds and waves.

There are also newer additions to the L2 product, which should make it easier to use. There is now a flag (orbit_type_01), at measurement level, describing the type of orbits used in the processing, this is particularly relevant for NRT data.

A new indexing scheme is available to allow easy matching between 1Hz and 20Hz data, the same approach used by EnviSat. The following variables were added: index_1hz_meas_20_[ku|c], index_first_20hz_meas_01_[ku|c] and num_20hz_meas_01_[ku|c].

There are improvements on the wet tropospheric correction, especially near the coast, as the 5-parameter algorithm was improved, and the backscatter coefficient is now corrected for attenuation, bringing Sentinel-3 in line with other altimeter product formats.

Improvements on sea ice detection are also part of the updates of this Processing Baseline.

Level 2 products now include internal netCDF compression, reducing the file size by about 50%. In addition, the Sentinel-3 Marine Data Centre at EUMETSAT will now produce data over the North American Great Lakes, Lake Victoria, and the Caspian Sea.

At Level 1, the averaging period for the calibrations has been prolonged to provide smoother calibration and less noisy data. Also at SRAL L1 the number of stack beams is now set to 180 instead of 174.

The updated Product Data Format Specification - SRAL/MWR Level 1 & 2 Instrument Products (PDF, 11 MB) is now available.

There are also several anomalies fixed, details can be found in S3 Product Notice – Altimetry (PDF, 1 MB) and Sentinel-3A Product Notice – STM L2 Marine (NRT, STC and NTC) (PDF, 329 KB)

For more information, contact our User Service Helpdesk.

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