NOAA@NSIDC would like to make users aware of a data update and an error notice for the NOAA@NSIDC Gridded Monthly Sea Ice Extent and Concentration, 1850 Onward data set.
Error notice: A user has made us aware that the ice cover derived from the Danish Meteorological Institute Yearbooks may have been incorporated incorrectly into the Kelly grid source as it was used in G10010. The Kelly grids may have used the ice map from the subsequent month, rather than the intended month. The Kelly grids were used over April through August or September of 1901-1956. We are investigating the problem, and plan to correct the misalignment. We will inform registered users of the outcome. This apparent misapplication of the Kelly grid source is present in both V1 and V2.
Update notice: Gridded Monthly Sea Ice Extent and Concentration, 1850 Onward, has been updated from Version 1 to Version 2. Version 2 adds four years to the record, extending it through 2017, and improves the product with additions and corrections. These include use of a more accurate land mask, and the addition of csv files holding time series of arctic-wide and regional sea ice area and extent. Appendix 3 in the user guide outlines differences in sea ice extent and area between Version 1 and Version 2.
This data set contains observations from historical sources, gridded into a monthly sea ice concentration product beginning in 1850. Starting in 1979, the data are derived from a single source: concentration from satellite passive microwave data. The historical observations include ship observations, compilations by naval oceanographers, analyses by national ice services, and others. The data are provided in a 1/4 degree latitude by 1/4 degree longitude grid and in NetCDF-4 format.
These data are suitable for analyzing long-term trends in Arctic ice extent. In the figure below, red shades are negative anomalies, blue are positive. The data show the response of Arctic sea ice to Arctic warming in the industrial age.
To access the new data and the user guide, please visit the data set landing page.
Data set DOI: https://doi.org/10.7265/jj4s-tq79