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Data Set ID:

Sea Ice Index, Version 1

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.

Geographic Coverage

Data Set Tabs

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
  • 1978-10-26
(updated daily)
Temporal Resolution:
1 day
  • Sea Ice > Ice Extent
  • Sea Ice > Ice Growth/Melt
  • Sea Ice > Sea Ice Concentration
Sensor(s): SMMR, SSM/I, SSMIS
Data Format(s):
  • PNG
  • ASCII Text (.txt)
  • ESRI Shapefile
Data Contributor(s): F. Fetterer, Kenneth Knowles, Walt Meier, Matthew Savoie

Data Citation

As a condition of using this 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. 2002, updated daily. Sea Ice Index, Version 1. [indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. [Date Accessed].

Questions? Please contact:

NSIDC User Services
Phone: 1 303 492-6199
Fax: 1 303 492-2468
Contact Address:
National Snow and Ice Data Center
University of Colorado
City: Boulder
Province or State: CO
Postal Code: 80309-0449
Country: USA