NOAA@NSIDC is pleased to announce the release of Sea Ice Index, Version 4. This new version uses input data from the JAXA GCOM-W1 AMSR2 instrument for 1 January 2025 through forward processing. Input sea ice concentration fields from AMSR2-using NSIDC-0803 now replace those from SSMIS-using NSIDC-0081 and NSIDC-0051.
This change was driven by the upcoming loss of access to SSMIS data and the degradation observed in current SSMIS data, as these instruments are well past their designed lifespan. All Version 4 data prior to 1 January 2025 are identical copies of the Version 3 data, just with v4.0 in the filenames.
The main changes in this new version include the following:
- AMSR2 data now serves as input for the Sea Ice Index data record of images and extent/area numbers starting 1 January 2025
- Elimination of the distinction between near-real-time (NRT) and final data
- Processing includes temporal interpolation on input NSIDC-0803 ice concentration fields to fill gaps in derived sea ice extent and concentration images and GeoTIFFs
- Minor adjustment in Arctic pole hole size
For full details, see Special Report 28: Sea Ice Index Version 4 Analysis.
You can access the data, documentation, and citation information here:
https://nsidc.org/data/G02135/versions/4
Data set DOI: https://doi.org/10.7265/a98x-0f50