by DMI, July 2017

The model has been updated in 2014 to better account for meltwater refreezing in the snow, and again in 2015 to account for the lower reflectivity of sunlight in bare ice than in snow. Finally, it has been updated again in 2017 with a more advanced representation of percolation and refreezing of meltwater. At the same time, we have extended the reference period to 1981-2010. The update means that the new maps, values and curves will deviate from the previous ones. Everything shown on this site, however, is calculated with this new model, so that all curves and values are comparable.

See also here