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Update of OSI SAF NetCDF format for Sea Ice Concentration, Edge and Type products

All OSI SAF Sea Ice products are available on NetCDF3 format. The content of these NetCDF files have been updated in May 2012 for the Sea Ice Concentration, Edge and Type products (OSI-401, OSI-402 and OSI-403), as well as the file name convention. The reprocessed Sea Ice Concentration product (OSI-409) and LR Sea Ice Drift (OSI-405) product have not been changed. The reason for these changes is to provide all ice products using the same meta data convention (CF-1.4) and to harmonize the content of these three products with the more recent released OSI-405 and OSI-409 products.

To assure that the users have good time to adapt to the new format specifications, the old format will be provided in parallel with the new format until 15th September 2012.

Availability of new and old files

The old files are available on the FTP server under these directories:

  • Concentration files: ftp://osisaf.met.no/prod_netcdf/ice/conc
  • Edge files: ftp://osisaf.met.no/prod_netcdf/ice/edge
  • Type files: ftp://osisaf.met.no/prod_netcdf/ice/type

    The new files are available on the FTP server under these directories:

    Latest 31 days:

  • Concentration files: ftp://osisaf.met.no/prod/ice/conc
  • Edge files: ftp://osisaf.met.no/prod/ice/edge
  • Type files: ftp://osisaf.met.no/prod/ice/type


  • Concentration files: ftp://osisaf.met.no/archive/ice/conc/{year}/{month}
  • Edge files: ftp://osisaf.met.no/archive/ice/edge/{year}/{month}
  • Type files: ftp://osisaf.met.no/archive/ice/type/{year}/{month}

    Changes in format name

    Old file name convention:

  • Concentration: ice_conc_{area}_{date12}.nc
  • Edge: ice_edge_{area}_{date12}.nc
  • Type: ice_type_{area}_{date12}.nc

    New file name convention:

  • Concentration: ice_conc_{area}_polstere-100_multi_{date12}.nc
  • Edge: ice_edge_{area}_polstere-100_multi_{date12}.nc
  • Type: ice_type_{area}_polstere-100_multi_{date12}.nc

    {area} is nh for the Northern Hemisphere products and sh for Southern Hemisphere.
    {date12} is datestring with 12 digits.

    Changes in file content

    The new files are described in the updated Product User Manual v3.8.

    These are the most important changes in the file content:

  • Time variable is double, not integer.
  • New variable time_bnds for time boundaries.
  • New dimension nv for variable time_bnds.
  • New coordinate variables xc and yc.
  • Sea Ice Concentration variable name has changed to ice_conc (previously ice_concentration).
  • Have replaced variable quality_index with variable status_flag, which provides some new information.
  • Grid mapping variable name and type has change to Polar_Stereographic_Grid and integer (previously polar_stereographic and character type).
  • Improved and extended global attributes.
  • Improved and extended variable attributes.


    For more questions or comments to the new format, contact person is the OSI SAF Sea Ice manager Steinar Eastwood, met.no, osisaf-manager[at]met.no.