This is the most recent version of these data.
In general, the V2 extent and area values are slightly higher than those derived from V1 (Figure 24). To create V1.1, inconsistencies in the V1.0 land mask were addressed by applying an “if ever land, always land” rule to grid cells. This had the effect of slightly expanding the land mask, so that the area covered by ocean cells, and thus the area that could contain sea ice, was proportionally reduced. The improved V2 land mask leaves more ocean cells in which ice may occur. In total, about 450,000 sq km of coastal ocean are added. V2 ice extent and area differ from extent and area derived using V1, simply because the V1 and V2 land areas are not the same. This difference is greatest in the winter months, when ice reaches a greater expanse of coastline.
Most of the higher V2 extent and area values are the result of the changed land mask, with the change in input CDR source data version being an additional factor in the satellite era. There is a seasonal effect in the change attributable to the improved land mask