NOTICE 10/19/17: Sea Ice Index now Version 3.0.
Read more ...

Sea Ice Index Data and Image Archive

Data and Image Archive

Here you can access the archived monthly and daily Sea Ice Index images and data as well as the input data from which the Sea Ice Index is derived.

All archived data reside in the following FTP location: ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/

The Sea Ice Index archive contains the following:

  • Monthly images of extent, concentration, anomalies, and trends from November 1978 through last month.
  • Daily images of extent and concentration.
  • Monthly sea ice extent and area data files.
  • Monthly GIS compatible shapefiles of ice extent.
  • Monthly and daily GIS compatible shapefiles of median ice extent.
  • Daily sea ice extent data files and daily climatology data files with data from November 1978 through yesterday.

Monthly Images

Monthly concentration, extent, anomaly, and trend images are availabe from the archive.

Access files:

  1. Go to either the North or South FTP monthly images directory.
  2. Choose the month directory (indicated by a 2-digit and 3-character month abbreviation) for the data that you are interested in.
  3. Within the month directory, search for the year and type of monthly image files that are named according to the following convention:
    H_yyyymm_type_[blmrbl]_[hires]_vx.x.png
    Where H stands for the hemisphere: N (north) or S (south); yyyy is the 4-digit year; mm is the 2-digit month; [blmrbl] if present, indicates the image uses the bluemarble background; [hires] if present, indicates the image is high resolution; vx.x is the version number; and type is the type of image in the file: extn (extent), conc (concentration), anom (concentration anomalies), and trnd (concentration trends).

Daily Images

Daily concentration and extent are available from the archive.

Access files:

  1. Go to either the North or South FTP daily images directory.
  2. Choose a year directory (indicated by the 4-digit year) and then the month directory (indicated by a 2-digit and 3-character month abbreviation) for the data that you are interested in.
  3. Within the month directory, search for the year and type of monthly image files that are named according to the following convention:
    H_yyyymmdd_type_[blmrbl]_[hires]_vx.x.png
    Where H stands for the hemisphere: N (north) or S (south); yyyy is the 4-digit year; mm is the 2-digit month; dd is the 2-digit day of month; [blmrbl] if present, indicates the image uses the bluemarble background; [hires] if present, indicates the image is high resolution; vx.x is the version number; and type is the type of image in the file: extn (extent) and conc (concentration).

GIS Compatible Files (shapefiles)

Monthly Extent Shapefiles

Monthly extent shapefiles are available for Northern and Southern hemispheres, for November 1978 to present, both as polygons and polylines.

Access files:

  1. Go to either the North or South FTP monthly extent shapefiles directory.
  2. Choose a month directory (indicated by a 2-digit and 3-character month abbreviation). 
    Shapefiles are organized in monthly directories by extent for that month and year. Files are zipped.
Monthly and Daily Median Shapefiles

Each month's or day's shapefile indicates that month's or day's median extent for the period 1981 to 2010. Shapefiles are available for Northern and Southern hemispheres, polylines only.

Access files:

Monthly

  1. Go to either the North or South FTP monthly median shapefiles directory.
  2. All monthly median files are within that directory. Files are zipped.

Daily

  1. Go to either the North or South FTP shapefiles directory.
  2. All daily median files are within that directory. Files are zipped.

Google Earth Files (.kmz)

Compare satellite images of September sea ice minimum extents for the last thirty years for both the Arctic and the Antarctic.

September sea ice extent, 1979 - present (KMZ, 343 KB)

View Arctic and Antarctic sea ice extents from 1979 through present for the months March (maximum sea ice extents) and September (minimum sea ice extents). Note: September is the default month when the file is opened. To see March, click on the March layer in the Google Earth side panel.

Minimum and Maximum Sea ice extents, 1979 - present (KMZ, 1.8 MB)

Monthly Sea Ice Extent and Area Data Files

The ASCII data files tabulate extent and area (in millions of square kilometers) by year for a given month.

Access files:

  1. Go to either the North or South FTP monthly data directory.
  2. Choose the monthly file you are interested in, which are named according to the following convention:
    H_mm_extent_vx.x.csv
    Where H stands for the hemisphere: N (north) or S (south), and mm is the 2-digit month.

Daily Sea Ice Extent Data Files

These files provide the total extent for each day for the entire time period for both hemispheres. The data files are in comma delimited ASCII text format (.csv).

Access files:

Daily Climatology Data Files

These files contain the daily average extent data for 1981 to 2010. They comprise the data for the solid grey line and the light grey standard deviation swath in the Daily Total Sea Ice Extent Time Series Graph. The data files are in comma delimited ASCII text format (.csv).

Access files:

Passive Microwave Sea Ice Concentrations

These data are not part of the Sea Ice Index archive. They are the input data that the Sea Ice Index is derived from. To access these data and learn more about them, see the following links: