extent https://nsidc.org/cryosphere/seaice/data/terminology.html differences in extent and area defines extent differences in extent and area NSIDC “Sea ice extent” differences in extent and area sea ice concentration sea ice concentration Sea ice extent sea ice concentration differences in extent and area differences in extent and area differences in extent and area differences in extent and area differences in extent and area differences in extent and area the “terminology” page differences in extent and area differences in extent and area differences in extent and area differences in extent and area differences in extent and area differences in extent and area differences in extent and area differences in extent and area sea ice concentration differences in extent and area