Until now, climate diagnostic applications, reanalyses, and atmospheric modeling studies that needed a lower boundary condition did not have an arctic-wide gridded ice concentration data set to use based on observations and one that extends back as far as the mid-nineteenth century. Gridded Monthly Sea Ice Extent and Concentration, 1850 Onward addresses this need by improving and extending the Arctic and Southern Ocean Sea Ice Concentrations product. It does this by adding newly available historical sources and by using the NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration for the satellite era.
The NOAA@NSIDC product, Gridded Monthly Sea Ice Extent and Concentration, 1850 Onward, uses the following data sources:
- North Atlantic ice edge positions covering 1850 through 1978 derived from various sources, including newspapers, ship observations, aircraft observations, diaries, and more.
- Gridded ice concentration from regular aerial surveys of ice in the eastern arctic by the Arctic and Antarctic Research Institute, St. Petersburg, Russia, beginning in 1933.
- Ice edge positions for Newfoundland and the Canadian Maritime Region from observations over the period 1870 through 1962.
- Detailed charts of ice in the waters around Alaska for 1954 through 1978 called the The Dehn Collection of Arctic Sea Ice Charts, 1953-1986.
- Arctic-wide maps of ice cover from the Danish Meteorological Institute over 1901-1956.
- Whaling logbook entries noting ship position along with an indication of whether the ship was in the presence of ice.
The six sources already existed as data compilations in one form or another prior to our use of them, and with the exception of the Canadian ice edge positions and the whaling logbook data, these are available from the National Snow and Ice Data Center. However, some data sets, such as the Dehn collection, required digitization and interpretation before the information could be used. The documentation for Gridded Monthly Sea Ice Extent and Concentration, 1850 Onward provides references for all sources and details how each was prepared for processing. The data product is a NetCDF file covering January 1850 through December 2013. It will be updated and extended in 2017.
More information can be found in the July 2016 Geographical Review article cited below, and in a Cooperative Institute for Research in Environmental Sciences (CIRES) news article called Reconstructing Arctic History: Scientists build a new database to depict Arctic sea ice variations back to 1850. CIRES is a partnership of NOAA and CU-Boulder. The National Snow and Ice Data Center is part of CIRES.
Walsh, John E., Florence Fetterer, J. Scott Stewart, and William L. Chapman. 2016. A database for depicting Arctic sea ice variations back to 1850. Geographical Review. doi: 10.1111/j.1931-0846.2016.12195.x.
Data Set DOI: http://dx.doi.org/10.7265/N5833PZ5