| Time-variable GRACE (Gravity Recovery and Climate Experiment) gravity field solutions
are routinely exploited to derive secular and seasonal mass changes on and near the Earth’s
surface. However, the quantification of mass redistribution from space gravimetry is not a
straightforward process. For instance, published linear deglaciation rates of the
Greenland ice sheets vary from -100 Gt/yr to -300 Gt/yr; the discrepancies are subject
to applied methodologies, the considered gravity field time-series and the period
of investigation. Furthermore, in the recent past discussion has come to the fore
whether the temporal behavior of mass variation might be better represented by a
second-order polynomial rather than a linear regression model. In summary, the
degrees of freedom inherent to GRACE analysis make the detection of mass trends to
become a delicate topic. This contribution sensitizes for a more critical and profound
examination of trends derived from GRACE mass-variation time-series. We point to
possible misinterpretation and propose “rules” to improve the consistency of results. |