Greenland mass change using range acceleration from GRACE-FO

Abstract

Abstract. Observations of ice mass change with GRACE and GRACE-FO are limited in both temporal and spatial resolution. For the Greenland ice sheet, standard processing can resolve monthly mass change at the scale of large drainage basins, not at the level of individual glaciers or smaller regions. For GRACE-FO, a method using the range acceleration measurements to calculate instantaneous line-of-sight gravity has been used to study hydrological extremes such as floods and storm surges. In this paper, we look at the Greenland ice sheet and use the line-of-sight gravity signal to estimate 5-day mass change for four summers. We also include altimetry data to try to improve the spatial resolution of the observed mass change. The amplitude of the estimated mass change is within the range of monthly mass change estimates. The choice of regularisation clearly affects the spatial distribution, which in turn affects estimates at basin scales or even at smaller scales. Additionally, the noise level increases relative to the monthly signal, and the regularisation based on altimetry data increases the correlation among mass points compared to Tikhonov regularisation. Estimating mass change based on line-of-sight gravity is possible, although the spatial distribution remains sensitive to the choice of regularisation. Nonetheless, the approach shows promise for resolving short‑term mass‑change events and motivates further refinement of line-of-sight gravity-based inversion techniques for future satellite gravimetry missions.