Notice Regarding Data Corrections

Reprocessing is complete and updated data are now available through 31 December 2012 for all Sea Ice Trends and Sea Ice Trends and Climatologies from SMMR and SSM/I-SSMIS data sets. With this update, the following changes have been implemented:

Total Ice-Covered Area and Extent
  • The cutoff value which defines a region as ice-covered or not ice-covered has been adjusted from 14.8 percent to 15 percent to more closely match the methodology used to calculate other sea ice extent and area products at NSIDC.
Ice Persistence and Monthly Climatology of Sea Ice Concentration (Monthly Means)
  • Includes the new 15 percent cutoff value described above.
  • To prevent inconsistencies between different algorithms, these parameters are now calculated exclusively using the NASA team algorithm.
Monthly Ocean Masks and Maximum Extent Masks
  • The ocean mask files and maximum extent mask files have been temporarily removed as they are not the masks used in the production of these data sets. NSIDC is currently standardizing masks across all sea ice products and will distribute the replacement masks as soon as they are available.

This most recent reprocessing also rectifies two previous releases of these data sets that contained erroneous data. In January/February of 2012, and May of 2013, the products were to have contained data from 2007 to 2010 and from 2010 to 2011, respectively. However, the climatology products contained data only through 2007. We recommend replacing previously downloaded 2010 and 2011 climatology data files with the climatology files that now extend through 2012. The Total Ice-Covered Area and Extent data set did contain post-2007 data, but reprocessed data utilizing the new methodology are available in the 2012 release.

For more information or help with these data sets, please contact NSIDC User Services.

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