Sea Ice Concentration CDR Version 4 Now Available

NOAA@NSIDC is pleased to announce that the NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 4 data set, accessible through the National Snow and Ice Data Center (NSIDC), is now available. The main changes in this new version are:

  1. The daily Climate Data Record (CDR) sea ice variable now spans 25 October 1978 through to the most recent processing, and the monthly CDR variable now spans from November 1978 through to the most recent processing.
  2. NSIDC-produced daily and monthly NASA Team (NT) and NASA Bootstrap (BT) variables are included.
  3. Four variables in the daily files and four variables in the monthly files have been renamed.
  4. The Goddard-produced variables have been removed.
  5. Yearly aggregated files containing daily data and period-of-record aggregated files containing monthly data are available, in addition to the daily and monthly NetCDF files.
  6. Gap filling implemented using spatial and temporal interpolation. Two new flag variables indicate when interpolation has been done.
  7. Arctic pole hole filled by spatial interpolation.
  8. NSIDC’s BT algorithm updated to version 3.1.
  9. Updated the NASA Team weather filter threshold for the Southern hemisphere instruments.
  10. In addition to the BT weather and land spillover filters, the NT filters are now also applied.
  11. Individual land masks have been merged into one composite land mask.

For further details on all these changes, a full overview of this new version and comparisons with version 3, we recommend reading NSIDC Special Report 20.

Note that Version 3 will remain available through December 2021 at:

Access to the Version 4 data and documentation is provided on the data set web page at NSIDC.

Data Set DOI:

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