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Data Set ID:
G02135

Sea Ice Index, Version 2

The Sea Ice Index provides a quick look at Arctic- and Antarctic-wide changes in sea ice. It is a source for consistent, up-to-date sea ice extent and concentration images, in PNG format, and data values, in ASCII text files, from November 1978 to the present. Sea Ice Index images also depict trends and anomalies in ice cover calculated using a 30-year reference period of 1981 through 2010.

The images and data are produced in a consistent way that makes the Index time-series appropriate for use when looking at long-term trends in sea ice cover. Both monthly and daily products are available. However, monthly products are better to use for long-term trend analysis because errors in the daily product tend to be averaged out in the monthly product and because day-to-day variations are often the result of short-term weather.

Monthly extent products are also available as geographic information systems (GIS) compatible shapefiles. Data are available via FTP.

Version Summary:

The Sea Ice Index has been updated to Version 2. Changes include using the most recently available version of the GSFC input sea ice concentration data and adjusting three procedures in the Sea Ice Index processing routine. These four updates affected different sections of the Sea Ice Index time series. All of them affected the final monthly data and two of them affected the final daily data. Additionally, two of the updates affected the near-real-time monthly data and one of them affected the near-real-time daily data. See the Sea Ice Index Version 2 documentation for complete details.

Geographic Coverage

Spatial Coverage:
  • N: -39.23, S: -90, E: 180, W: -180

  • N: 90, S: 30.98, E: 180, W: -180

Spatial Resolution:
  • 25 km x 25 km
Temporal Coverage:
  • 26 October 1978
(updated daily)
Temporal Resolution: 1 day
Parameter(s):
  • Sea Ice > Ice Extent
  • Sea Ice > Ice Growth/Melt
  • Sea Ice > Sea Ice Concentration
Platform(s) DMSP, DMSP 5D-3/F17, DMSP 5D-3/F18, NIMBUS-7, SATELLITES
Sensor(s): SMMR, SSM/I, SSMIS
Data Format(s):
  • PNG
  • ASCII Text (.txt)
  • ESRI Shapefile
Version: V2
Data Contributor(s): F. Fetterer, Kenneth Knowles, Walt Meier, Matthew Savoie

Data Citation

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Fetterer, F., K. Knowles, W. Meier, and M. Savoie. 2016, updated daily. Sea Ice Index, Version 2. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5736NV7. [Date Accessed].
Questions? Please contact:

NSIDC User Services
Phone: 1 303 492-6199
Fax: 1 303 492-2468
Email: nsidc@nsidc.org
Contact Address:
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
City: Boulder
Province or State: CO
Postal Code: 80309-0449
Country: USA