Change to processing standard of Jason-3 data

The Jason-3 altimeter products generated by EUMETSAT will be updated to the new GDR-F standard on 29 October 2020.

Tuesday, 13 October 2020

Since the launch of Jason-3, the GDR-D altimetry product standard has been used to process Jason-3 data. GDR-D will be replaced by the new GDR-F standard on 29 October 2020. This new standard will also be used to process the future Sentinel-6 Michael Freilich data, thus facilitating multi-mission cross-calibration activities.

EUMETSAT generates the following near-real time Jason-3 altimeter products, known as Operational Geophysical Data Records (OGDRs):

OGDR in netCDF
OGDR in BUFR
OGDR Sea Surface Height Anomaly (SSHA) in netCDF

The upgrade to the new GDR-F standard will mostly affect the netCDF products, and will include the following changes (non-exhaustive list):

  • Improved algorithms for product generation and calibration.
  • New quality flags added.
  • Fix to known anomalies.
  • Use of WGS84 instead of Jason-1 ellipsoid.
  • New product fields added, like distance to the coast
  • Introduction of the netCDF version 4 format and compression for the output products.
  • Some variable names modified.

For the BUFR product, which is generated from the netCDF product, certain variables (those that will be removed in the GDR-F netCDF product) will be left empty after the change. The format of the BUFR product remains unchanged.

Full details on the changes will be provided in updated versions of the Jason-3 Products Handbook and Jason-3 Products Specification document.

Filenames will also change to reflect the new standard. The letter representing the version will change from d to f.

Example filenames for the netCDF products

netCDF OGDR

Current filename: JA3_OPN_2PdS168_068_20200901_231031_20200902_010647.nc.bz2
New filename: JA3_OPN_2PfS168_068_20200901_231031_20200902_010647.nc.bz2

netCDF OGDR-SSHA

Current filename: JA3_OPR_2PdS168_068_20200901_231031_20200902_010647.nc.bz2
New filename: JA3_OPR_2PfS168_068_20200901_231031_20200902_010647.nc.bz2

Example filenames for BUFR products

Current filename: W_XX-EUMETSAT-Darmstadt,SURFACE+SATELLITE,JASON3+OGDR_C_EUMS_20200902012947_d_168_068_20200902010647
New filename: W_XX-EUMETSAT-Darmstadt,SURFACE+SATELLITE,JASON3+OGDR_C_EUMS_20200902012947_f_168_068_20200902010647

Sample files in netCDF, generated with the new standard, are now available via our ftp server, BUFR sample files will follow shortly.

For more information, contact our User Service Helpdesk.

 
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