On the quantification of ice sheet mass changes and glacial isostatic adjustment effects by combining satellite data

• Main Author: Willen, Matthias Oskar
• Other Authors: Horwath, Martin, Pail, Roland, Sasgen, Ingo, Technische Universität Dresden
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2022
• Subjects: satellite geodesy; ice sheets; mass balance; glacial isostatic adjustment; inverse problem; Satellitengeodäsie; Eischilde; Massenbilanz; Glazial-isostatische Anpassung; Inverses Problem; info:eu-repo/classification/ddc/910; ddc:910; Antarctic; Greenland; The Antarctic; Antarc*; Antarctica; Ice Sheet
• Online Access: https://nbn-resolving.org/urn:nbn:de:bsz:14-qucosa2-839733; https://tud.qucosa.de/id/qucosa%3A83973; https://tud.qucosa.de/api/qucosa%3A83973/attachment/ATT-0/

The satellite gravimetry mission Gravity Record And Climate Experiment (GRACE), which was operational from 2002 to 2017, and its follow-on mission GRACE-Follow-On (GRACE-FO), which has been active since 2018, revolutionized the observation of temporal changes of the Earth's gravitational field. The measurement data from these missions enable the nuanced quantification of mass redistributions on Earth. Water redistributions between continents and oceans caused by climate change are of particular research interest because of their relevance for mankind. These are, for example, the ice mass changes (IMC) of the ice sheets in Antarctica and Greenland, which this work focuses on. IMC estimates derived from satellite gravimetry data, like from other quantification methods, confirm that both the Greenland Ice Sheet (GIS) and the Antarctic Ice Sheet (AIS) have been losing mass over the last two decades. However, these estimates are subject to large uncertainties, which is particularly the case for the AIS. If the mass balance is obtained from gravimetric observations, a major source of uncertainty is the consideration of effects due to glacial isostatic adjustment (GIA). The uncertainty of the present-day gravitational field changes caused by the isostatic adjustment of the solid Earth to IMC during the last centuries and millennia propagates into estimates of the recent IMC. According to results of the Ice sheet Mass Balance Inter-comparison Exercise (IMBIE), the spread of different modelling results predicting the GIA-induced mass effect in Antarctica is almost as large as the estimated rate of the IMC itself. In Greenland, the spread of the mass effect from different GIA modelling results is approximately 20 % of the rate of IMC. Alternatively, the IMC can be determined using surface elevation changes derived from satellite altimetry observations. In this case, any GIA error hardly affects the results, but there is a significant source of uncertainty in the conversion of volume changes into mass changes. It is ...