NOAA@NSIDC would like to announce that at the end of April/beginning of May 2021, version 4 of the NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration data set will be released. Please note version 3 will be available for 6 months after the release of version 4. For more information about specific changes, please see the user announcment.
Data Set ID:

NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 3

This data set provides a Climate Data Record (CDR) of sea ice concentration from passive microwave data. The CDR algorithm output is a rule-based combination of ice concentration estimates from two well-established algorithms: the NASA Team (NT) algorithm (Cavalieri et al. 1984) and NASA Bootstrap (BT) algorithm (Comiso 1986). The CDR is a consistent, daily and monthly time series of sea ice concentrations from 09 July 1987 through the most recent processing for both the north and south polar regions. In addition, three other sea ice concentration products are included with the CDR that extend the sea ice measurements back to 01 November 1978. However, these three products are not included in the official CDR because processing the older data in a way that follows the standards of a CDR is not currently possible. All data are on a 25 km x 25 km grid.

Note: A near-real-time version of this data set also exists to fill the gap between the time that this data set is updated through to the present. The data set is called the Near-Real-Time NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration (

This is the most recent version of these data.

Version Summary:

Version 3 of the sea ice CDR is created with a new version of the input product, Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data and uses a new valid sea ice mask for the Northern Hemisphere.

  • Sea Ice > Sea Ice Concentration > SEA ICE CONCENTRATION
Data Format(s):
  • NetCDF
Spatial Coverage:
N: -39.36, 
N: 89.84, 
S: -89.84, 
S: 31.1, 
E: 180, 
E: 180, 
W: -180
W: -180
Platform(s):DMSP 5D-2/F11, DMSP 5D-2/F13, DMSP 5D-2/F8, DMSP 5D-3/F17, DMSP 5D-3/F18, Nimbus-7
Spatial Resolution:
  • 25 km x 25 km
Sensor(s):SMMR, SSM/I, SSMIS
Temporal Coverage:
  • 1 November 1978 to 31 December 2019
Temporal Resolution1 day, 1 monthMetadata XML:View Metadata Record
Data Contributor(s):Walter Meier, F. Fetterer, Ruth Duerr, Julienne Stroeve, Matthew Savoie, Sean Mallory

Geographic Coverage

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FTP data can be downloaded through a Web browser (Firefox or Edge are recommended) or command line via FTP. For help downloading data through an FTP client, go to the How to access data using an FTP client support page.

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.

Meier, W. N., F. Fetterer, M. Savoie, S. Mallory, R. Duerr, and J. Stroeve. 2017. NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 3. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: [Date Accessed].

Literature Citation

As a condition of using these data, we request that you acknowledge the author(s) of this data set by referencing the following peer-reviewed publication.

  • Peng, G., W. N. Meier, D. Scott, and M. Savoie. 2013. A long-term and reproducible passive microwave sea ice concentration data record for climate studies and monitoring, Earth Syst. Sci. Data. 5. 311-318.

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Descriptions of and Differences between the NASA Team and Bootstrap Algorithms
NSIDC currently archives passive microwave sea ice concentration products based on two algorithms: the NASA Team algorithm and the Bootstrap algorithm. Both algorithms were developed by researchers at the NASA Goddard Space Flight Center in the 1980s. Provided below are two short summaries of the... read more

How To

How to access NOAA@NSIDC data sets in PolarWatch
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