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Data Set ID:

Near-Real-Time SSM/I-SSMIS EASE-Grid Daily Global Ice Concentration and Snow Extent, Version 4

The Near-Real-Time SSM/I-SSMIS EASE-Grid Daily Global Ice Concentration and Snow Extent product (Near-real-time Ice and Snow Extent, NISE) provides daily, global near-real-time maps of sea ice concentrations and snow extent. The National Snow and Ice Data Center (NSIDC) creates the current NISE product using passive microwave data from the Special Sensor Microwave Imager/Sounder (SSMIS) on board the Defense Meteorological Satellite Program (DMSP) F17 satellite. The SSMIS instrument is the next generation Special Sensor Microwave/Imager (SSM/I) instrument. These data are not suitable for time series, anomalies, or trends analyses. They are meant to provide a best estimate of current ice and snow conditions based on information and algorithms available at the time the data are acquired. Near-real-time products are not intended for operational use in assessing sea ice conditions for navigation. Sea ice concentration and snow extent maps are provided in two 25 km azimuthal, equal-area projections: the Southern Hemisphere 25 km low resolution (SL) and Northern Hemisphere 25 km low resolution (NL) Equal-Area Scalable Earth-Grids (EASE-Grids). The NISE product is updated daily using the best available data from the past five days. Data are in Hierarchical Data Format - Earth Observing System (HDF-EOS) format and browse files are in GIF and HDF formats. HDF-EOS data files are available from 04 May 1995 through the present. Data in both formats are updated daily and are available via FTP.

Version Summary:
  • Updated metadata field values for PGEVERSION (collection level remains
    Version 4)

  • Removed 15% sea ice concentration threshold that assigned pixels
    with a sea ice concentration of <15% as ocean (data value of 255)

  • Reprocessed NISE Version
    4 to include sea ice concentration values of 1-14%

This revision is an update to NISE Version 4. All
Version 4 data (17 August 2009 - present) have been reprocessed
with this system.

Geographic Coverage

Data Set Tabs

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

Spatial Resolution:
Not Specified
Temporal Coverage
  • 4 May 1995
Temporal Resolution:
1 day
  • Sea Ice > Ice Extent
  • Snow/Ice > Ice Extent
  • Sea Ice > Sea Ice Concentration
  • Snow/Ice > Snow Cover
DMSP 5D-2/F13, DMSP 5D-3/F17
Sensor(s): SSM/I, SSMIS
Data Format(s):
Data Contributor(s): Anne Nolin, Richard Armstrong, Jim Maslanik

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.

Nolin, A. W., R. Armstrong, and J. Maslanik. 1998. Near-Real-Time SSM/I-SSMIS EASE-Grid Daily Global Ice Concentration and Snow Extent, Version 4. [indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. http://dx.doi.org/10.5067/VF7QO90IHZ99. [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
University of Colorado
City: Boulder
Province or State: CO
Postal Code: 80309-0449
Country: USA