NOAA@NSIDC is pleased to announce the release of the U.S. National Ice Center Arctic and Antarctic Sea Ice Charts in SIGRID-3 Format, Version 1 data set. This data set contains Arctic and Antarctic-wide sea ice charts that have information on sea ice concentration, stage of development (often called ice type), and form. The charts are produced by the U.S. National Ice Center, with a temporal coverage of 2003 to present, and for most of the record the charts are weekly in frequency. The charts are in SIGRID-3 format, which includes a shapefile (.shp) with associated files (.dbf, .prj, and .shx) and a metadata file (.xml, .shp.xml, or .txt).
Operational sea ice charts show ice regimes as distinct polygons within a mapped region. An ice regime is an area with a relatively consistent distribution of any mix of ice types and open water. Analysts at USNIC estimate the partial ice concentrations of various ice types in an ice regime, and encode the information according to a World Meteorological Organization standard.
The SIGRID-3 format carries all the information that analysts have encoded in an ice chart. This detailed information can be used to assign a level of risk to ice operations for ships with certain ice classes under the International Code for Ships Operating in Polar Waters, or Polar Code. Risk assessment for voyage planning must take into account whether ice in an area includes medium first-year ice or only thin first-year ice, for example.
Researchers who do not need the detail contained in the SIGRID-3 format may wish to use U.S. National Ice Center Arctic and Antarctic Sea Ice Concentration and Climatologies in Gridded Format, Version 1. This data set uses the SIGRID-3 files to make NetCDF, GeoTIFF, and Shapefile format weekly charts of total ice concentration, multiyear ice concentration, first-year ice concentration, thin ice concentration, and fast ice extent. In addition, there are period-of-record, 5-year and 10-year climatological averages.
These USNIC SIGRID-3 data join the Canadian Ice Service Regional Arctic Sea Ice Charts in SIGRID-3 Format, Version 1 data set, also archived at NSIDC.
Data set DOI: https://doi.org/10.7265/4b7s-rn93