Days 
  of Ice Cover
This 
  is a raster product showing the number of days with ice cover per pixel in the 
  specified time period. Days of ice cover is defined as the number of days with 
  ice concentration greater than 15 %. We commonly use 15 % as the boundary between 
  ice and open water in passive microwave images when used for navigation.
  
  The product is based on the Sea Ice Concentration (SIC) product and is stored 
  as 1 km resolution raster image.