Climate Data

Sea Ice Concentration data from NASA Goddard and NSIDC based on Bootstrap algorithm

Bootstrap sea ice refers to a well-known algorithm used to estimate sea ice concentration from passive microwave brightness temperatures. It can be applied to data from many satellite instruments, such as SMMR, SSMI, and AMSR-E. This page discusses the algorithm itself and the long-term data set ("NSIDC 0079, version 2") produced by J. Comiso and distributed by NSIDC. The latest version of the Bootstrap data set has been completely reprocessed so that SMMR and SSMI data are inter-calibrated with AMSR-E data. The Bootstrap data set provides a long-term, consistently interpreted and calibrated record for studies of climate variability and change, but users should be aware of uncertainties and possible biases.

Key Strengths:

  • Long-term (1978-almost present) record
  • Consistent algorithm through time
  • SMMR and SSMI concentrations are inter-calibrated to AMSR-E using varying tie points to account for changes in signatures of ice and open water due to changes in satellite instruments and platforms, or to physical effects

Key Limitations:

  • Influenced by temperature variability; very low temperatures can lead to underestimates
  • Underestimates concentration in cases of melt ponding

Years of Record

1978/10 to 2014/12
temporal metadataID:



Daily | Monthly

Data Time Period Extended?

yes, data set is extended

Spatial Resolution

25 x 25 km

Ocean or Land


Missing Data Flag

missing data present

Vertical Levels

Input Data


Earth system components and main variables

Suggested Data Citation

From NSIDC: Comiso, J. 1999, updated 2012. Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS, [list dates you used]. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media.

Usage Restrictions

unrestricted; registration requested
  1. Cho, K., N. Sasaki, H. Shimoda, T. Sakata, and F. Nishio. 1996. Evaluation and Improvement of SSM/I Sea Ice Concentration Algorithms for the Sea of Okhotsk. Journal Remote Sensing of Japan 16(2):47-58.
  2. Comiso, J. C., and F. Nishio. 2008. Trends in the Sea Ice Cover Using Enhanced and Compatible AMSR-E, SSM/I, and SMMR Data. Journal of Geophysical Research 113, C02S07, doi:10.1029/2007JC0043257.
  3. Comiso, J. C. 1995. SSM/I Concentrations Using the Bootstrap Algorithm. NASA Reference Publication 1380. 40 pages.

Key Figures

Click the thumbnails to view larger sizes



Climate Data Guide Image: Sea Ice Concentration data; Goddard Bootstrap Average Arctic sea ice concentration for March 2003-2007 according to the Bootstrap data set. Figure by D. Schneider.

Cite this page

National Center for Atmospheric Research Staff (Eds). Last modified 01 Mar 2016. "The Climate Data Guide: Sea Ice Concentration data from NASA Goddard and NSIDC based on Bootstrap algorithm." Retrieved from

Acknowledgement of any material taken from this page is appreciated. On behalf of experts who have contributed data, advice, and/or figures, please cite their work as well.