Data Set ID:

Gridded Monthly Sea Ice Extent and Concentration, 1850 Onward, Version 1

Observations from historical sources are the basis of this monthly gridded sea ice concentration product that begins in 1850. In 1979, these sources give way to a single source: concentration from satellite passive microwave data. The historical observations come in many forms: ship observations, compilations by naval oceanographers, analyses by national ice services, and others. Monthly sea ice concentration is given in a 1/4 degree latitude by 1/4 degree longitude grid. In addition to the concentration array, for each month a corresponding source array indicates where each of 16 possible sources is used. The file of concentration and source arrays conforms to NetCDF-4 standards.

Version Summary:

Initial data release.

Get Data


Data can be downloaded through a Web browser or command line via FTP. When using a Web browser, the FTP link first directs you to an Optional Registration Form that if filled out, will allow you to receive notifications about updates or processing changes related to that specific data set. After completing the Optional Registration Form, the FTP directory becomes available. For additional help downloading data through an FTP client, go to the How to access data using an FTP client support page.


Geographic Coverage

  • Sea Ice > Sea Ice Concentration
Spatial Coverage:
N: 89.9, 
S: 30.1, 
E: 180, 
W: -180
Spatial Resolution:
  • 1/4 degree x 1/4 degree
Temporal Coverage:
  • 1 January 1850 to 31 December 2013
(updated 2016)
Temporal Resolution: 1 month
Data Format(s):
  • NetCDF
Platform(s) DMSP, SHIPS
Version: V1
Data Contributor(s): John Walsh, William Chapman, Florence Fetterer

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.

Walsh, J. E., W. L. Chapman, and F. Fetterer. 2015, updated 2016. Gridded Monthly Sea Ice Extent and Concentration, 1850 Onward, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: [Date Accessed].

It appears your Web browser is not configured to display PDF files. Download adobe Acrobat or click here to download the PDF file.

No technical references available for this data set.
No FAQs or How Tos available for this data set.

Access complete Knowledge Base

Questions? Please contact:
NSIDC User Services
Phone: 1 303 492-6199