Data Set ID: 

Northern Hemisphere Seasonal and Intermittent Frozen Ground Areas 1901-2001, Version 1

This data set contains monthly values of the total exposed land area of seasonally frozen ground and
annual values for intermittently frozen ground in the Northern Hemisphere. Seasonally frozen ground is
defined as the near-surface soil that experiences freeze for more than 15 days per year, while intermittently frozen ground experiences fewer than 15 days of freeze per year. The values were
calculated based upon the monthly mean air temperature from the 1901-2002, 0.5 deg. global land
temperatures from the University of East Anglia Climate Research Unit (Mitchell and Jones, 2005) using
the technique described by Zhang, et al. (2003).

Two ASCII files are available. One file contains monthly values of seasonally frozen ground area in
square kilometers for 1901-2001. The other file contains annual values of intermittently frozen ground
area. Data are available via FTP.

This is the most recent version of these data.

BASIC Level of Service

Data: Data integrity verified

Documentation: Key metadata and links to supporting documentation available

User Support: Assistance with data access and basic data usage

See All Level of Service Details

  • Frozen Ground > Seasonally Frozen Ground > Freezing/Thawing Index
  • Frozen Ground > Seasonally Frozen Ground > SEASONALLY FROZEN GROUND
Data Format(s):
Spatial Coverage:
N: 90, 
S: 0, 
E: 180, 
W: -180
Platform(s):Not specified
Spatial Resolution:
  • 25 km x 25 km
Sensor(s):Not specified
Temporal Coverage:
  • 1 January 1901 to 31 December 2002
Temporal Resolution1 yearMetadata XML:View Metadata Record
Data Contributor(s):Tingjun Zhang

Geographic Coverage

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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.

T. Zhang, J. Smith 2006. Northern Hemisphere Seasonal and Intermittent Frozen Ground Areas 1901-2001, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: [Date Accessed].

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