Change to processing standard of Jason-3 data

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 are 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.

For more information, contact our User Service Helpdesk.