Northern Hemisphere EASE-Grid Weekly Snow Cover and Sea Ice Extent

Brief Description:

  • Northern Hemisphere EASE-Grid Weekly Snow Cover and Sea Ice Extent.

Temporal Coverage:

  • Monthly values for 1971/01 - 1995/12.
  • Long term monthly means, derived from data for years 1971 - 1995.

Spatial Coverage:

  • 1.0 degree latitude x 1.0 longitude (360x90).
  • 89.5N - 0.5N, 0.5E-359.5E.


  • Surface

Update Schedule:

  • Static

Download/Plot Data: (FTP Access)

Variable Statistic Level Download File Create Plot/Subset
Snowcover Monthly Mean Surface plot
' ' Monthly Long Term Mean Surface plot

Usage Restrictions:

  • None

Detailed Description:

  • Derived from the Northern Hemisphere EASE-Grid Weekly Snow Cover and Sea Ice Extent which combines snow cover and sea ice extent at weekly intervals for October 1978 through August 1995, and snow cover only for January 1971 through October 1978. (Sea ice data was not available prior to October 23, 1978.) This data set also includes monthly climatologies describing average extent, probability of occurrence, and variance. The data are provided in a 25 km grid, in an azimuthal, equal area projection (the NSIDC NL EASE-Grid). This dataset has been interpolated to a 1x1 grid.

    The snow cover extent is based on the digital NOAA-NESDIS Weekly Northern Hemisphere Snow Charts, revised by D. Robinson (Rutgers University) and regridded to the EASE-Grid. The original NOAA-NESDIS weekly snow charts are derived from the manual interpretation of AVHRR, GOES and other visible-band satellite data. Sea ice extent is based on the NSIDC polar stereographic sea ice concentration grids, derived from Scanning Multi-channel Microwave Radiometer (SMMR) and Special Sensor Microwave Imager (SSM/I) passive microwave brightness temperature data.

    Weekly values are binary where (1/0) indicated coverage or no coverage. Monthly percent of coverage values are calculated from the weekly values for that month and are therefore not integral. Additional information including references is available here.

  • Also, please read NSIDC's reference page


  • None

Related File Naming & Structure Information:

File Names:

  •   (In directory: /Datasets/snowcover/)

OpenDap File Names:

  • /thredds/dodsC//Datasets/snowcover/   

Dataset Format and Size:

  • PSL standard NetCDF 19.4 the monthly file.
  • PSL standard NetCDF .7 Mbyte file for the long term mean file.

Missing Data:

  • None.


  • Please note: If you acquire snowcover data products from PSL, we ask that you acknowledge us in your use of the data. This may be done by including text such as snowcover data provided by the NOAA/OAR/ESRL PSL, Boulder, Colorado, USA, from their Web site at / in any documents or publications using these data. We would also appreciate receiving a copy of the relevant publications. This will help PSL to justify keeping the snowcover data set freely available online in the future. Thank you!


  • Cavalieri, D. J., J. Crawford, M. Drinkwater, W. J. Emery, D. T. Eppler, L. D. Farmer, M. Goodberlet, R. Jentz, A. Milman, C. Morris, R. Onstott, A. Schweiger, R. Shuchman, K. Steffen, C. T. Swift, C. Wackerman, and R. L. Weaver. 1992. NASA sea ice validation program for the DMSP SSM/I: final report. NASA Technical Memorandum 104559. 126 pp.
  • Cavalieri, D. J., P. Gloersen, and W. J. Campbell. 1984. Determination of sea ice parameters with the NIMBUS-7 SMMR. Journal of Geophysical Research 89(D4):5355-5369.
  • Dewey, K. F., and R. Heim, Jr. 1981. Satellite observations of variations in Northern Hemisphere seasonal snow cover. NOAA Technical Report NESS 87. 83 pp.
  • Dewey, K. F., and R. Heim Jr. 1982. New data base: a digital archive of Northern Hemisphere snow cover. Presented at Western Snow Conference, April 19-23. Reno, NV, 9 pp.
  • Gloersen, P., W. J. Campbell, D. J. Cavalieri, J. C. Comiso, C. L. Parkinson, and H. J. Zwally. 1992. Arctic and Antarctic Sea Ice, 1978 - 1987: Satellite Passive Microwave Observations and Analysis. NASA SP-511.
  • Johannessen, O. M., M. W. Miles, E. Bjørgo. 1996. Global sea ice monitoring from microwave satellites. In IGARSS '96. 1996 International Geoscience and Remote Sensing Symposium. Remote Sensing for a Sustainable Future, ed. T. I. Stein, Vol. II: 932-934. Piscataway, NJ: Institute of Electrical and Electronics Engineers, Inc.
  • Knowles, K. 1992. Points, Pixels, Grids, and Cells: A Mapping and Gridding Primer. Unpublished report to the National Snow and Ice Data Center, Boulder, CO.
  • Robinson, D. A., K. F. Dewey, and R. R. Heim, Jr. 1993. Global snow cover monitoring: an update. Bull. Amer. Meteor. Soc. 74:1689-1696.
  • Swift, C. T., and D. J. Cavalieri. 1985. Passive microwave remote sensing for sea ice research. EOS 66(49):1210-1212.

Original Source:

  • NSIDC from Ken Knowles.


  • Physical Sciences Laboratory: Data Management
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    Boulder, CO 80305-3328