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OSI SAF sea ice concentration to be updated 4th July 2017

The OSI SAF sea ice concentration product (OSI-401-b) is being updated, due to previously announced spurious ice over open water. To deal with this spurious ice, a new filtered sea ice concentration field is being introduced to the OSI-401-b product. Spurious ice can occur in the OSI SAF sea ice concentration fields, due to weather effects and the uncertainty of the measurement over open water. The spurious ice is problematic for some users. The filtered product removes most of this spurious ice, at the cost of also removing some valid low concentration ice. The spurious ice is removed using two extra filters: a 2m air temperature and an open water filter. The updated product also contains information about which filters have been applied, in an update "status_flag" variable and and additional "masks" variable.
The filtered ice concentration field is described in the PUM and validation report. For more details about the current operational product, see: ./index.html#conc-ssmis>.

Previously, there was only one ice concentration field in the product. In the new version, you may choose from either the filtered or unfiltered variables:

  • For the new filtered ice concentrations field, continue to use the ice_conc variable, from either the netCDF, HDF5 or GRIB product files.
  • For the unfiltered ice concentrations field, use the ice_conc_unfiltered variable, from either the netCDF or HDF5 files. (The variable ice_conc_unfiltered was called ice_conc in the prior versions of the product.)

The unfiltered ice concentration field is no longer available in the GRIB file, as it has been replaced by the filtered one; it is recommended to use the netCDF product files to access the unfiltered ice concentration, if required.
As of 2017-06-13, the filtered files are available, in parallel with the existing operation product, for users to evaluate for a few weeks, from here:
The file names have the prefix filtered_. These, filtered, files will eventually replace the existing product (at ftp://osisaf.met.no/prod/ice/conc and EUMETCast) but without the filtered_ prefix.

This change will be implemented 4th July 2017.


For questions, please contact us on email osisaf-manager[at]met.no.