Arctic Sea Ice Phenology from Passive Microwave Satellite Retrievals

The seasonal timing of summer sea ice opening (sea ice contraction falls below 80%) and retreat (sea ice concentration falls below 15%), as well as fall sea ice advance (sea ice concentration rises above 15%) and closing (sea ice concentration rises above 80%) is recorded annually, as are the annual sea ice minimum, day of minimum, and the length of the open-water period (sea ice concentration continuously below 80%) and ice-free period (sea ice concentration continuously below 15%). Data inputs are daily sea ice concentration datasets from National Snow and Ice Data Center: Bootstrap v3 (https://nsidc.org/data/nsidc-0079/versions/3) and NASA-Team v2 (https://nsidc.org/data/nsidc-0051/versions/2). All data are stored in NetCDF4 files on the polar stereographic north grid with 25-km horizontal resolution.