The Greenland cryosphere is undergoing rapid changes,
and these are documented by remote sensing from space.
In this paper, an inversion scheme is used to derive mass
changes from gravity changes observed by GRACE, and
to derive the mean annual mass loss for the Greenland Ice
Sheet, which is estimated to be 204 Gt/yr for the period
2002-2010.
NASA’s laser altimetry satellite ICESat has provided elevation
estimates of the ice sheet since January 2003. In
order to be able to compare GRACE and ICESat derived
results, the ICESat volume change must be converted into
a mass change estimate. Therefore, it is necessary to
model the densities and compaction of the firn. We find
that data from ASIRAS show great potential for validating
the glaciological models used to determine the densities
and firn compaction.