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
Timestep
Data Time Period Extended?
Domain
Spatial Resolution
Ocean or Land
Missing Data Flag
Vertical Levels
Input Data
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.
Data Access: Please Cite data sources, following the data providers' instructions.
- binary: stand-alone gridded data set at NSIDC (ftp)
- netCDF: gridded data, distributed by NSIDC with Climate Data Record
- Area and Extent daily and monthly timeseries at NSIDC
- NSIDC pixel area grids and geocoordinate tools (needed to calculate sea ice extent & area)
- Extent timeseries from JAXA based on Bootstrap, multiple instruments (SMMR, SSMI, AMSR-E, Windsat)
Usage Restrictions
- 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.
- 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.
- Comiso, J. C. 1995. SSM/I Concentrations Using the Bootstrap Algorithm. NASA Reference Publication 1380. 40 pages.