New data for Arctic analysis available from NGA.
https://www.nga.mil/MediaRoom/PressReleases/Pages/NGA-provides-unclassified-geospatial-intelligence-...
http://nga.maps.arcgis.com/home/
http://nga.maps.arcgis.com/apps/PublicGallery/index.html?appid=dc06e1570de14885bb6c7adbaa5bfec5
