The Arctic Sea Ice Seasonal Change and Melt/Freeze Climate Indicators from Satellite Data, Version 1 data set, accessible through the NASA National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC), has been reprocessed and updated through the 2017 season. These updates correspond with a new minor version (Version 1.1). The data set was reprocessed to correct the continuous freeze onset (CFO) field, which mistakenly duplicated the early freeze onset (EFO) field in earlier versions. Geophysical data fields (year, xgrid, ygrid) were also renamed to better reflect common NetCDF practices (e.g. the year field was renamed as “time”).
This data set contains melt-season indicators that can be used to delineate various stages in the summer melt and freeze-up period of sea ice. The data are primarily derived from the NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration and DMSP SSM/I-SSMIS Daily Polar Gridded Brightness Temperatures data sets, both of which are also archived at NSIDC. The main parameters for this data set include the dates of melt onset, early melt onset, and continuous melt onset; dates of early and continuous freeze onset; days of opening, retreat, advance and closing; total outer and inner ice-free periods; seasonal loss-of-ice and gain-of-ice periods; and seasonal ice zone. The data are gridded on the NSIDC northern hemisphere polar stereographic grid at 25 km and available from 1 March 1979 through 28 February 2018.