Using GNSS to derive new information about Greenland and the Greenland Ice Sheet

• Main Author: Hansen, Karina
• Format: Book
• Language: English
• Published: Technical University of Denmark 2022
• Subjects: /dk/atira/pure/sustainabledevelopmentgoals/climate_action; name=SDG 13 - Climate Action; Arctic; Greenland; Jakobshavn Isbræ; Kangerlussuaq; Climate change; glacier; Ice Sheet; Jakobshavn; Jakobshavn isbræ
• Online Access: https://orbit.dtu.dk/en/publications/02159bdd-b927-4340-ab9c-a659b0361a1c; https://backend.orbit.dtu.dk/ws/files/310376060/DTU_Thesis_KarinaHansen_compressed.pdf

The Arctic is currently the region most susceptible to global climate change, experiencing the highest relative temperature rise. Furthermore, the possibility of rapid melt of the Greenland Ice Sheet (GrIS) is ranked among the most serious climate threats to our societies, with its potential contribution to global sea level rise regarded especially ominous. Completely melted the GrIS would be the equivalent to ∼7.4 m of global sea level rise. If the current increase in mass loss continues, the Greenland ice sheet alone may account for as much as ∼33 cm of global sea level rise by 2100, which is a significant increase compared to the ∼2.5 cm it contributed during the last century. The increased mass loss from the Greenland ice sheet and the growing interest in predicting future mass loss makes it increasingly important to unearth past climate, monitor the present and improve model predictions. This PhD project contributes to this by showing three new applications of existing Global Navigation Satellite System (GNSS) data that derive new information about Greenland and the GrIS. In the first study we presented a novel method to estimate the dynamic ice loss of Greenland’s three largest outlet glaciers: Jakobshavn Isbræ, Kangerlussuaq and Helheim. We measured the elastic displacements of the solid Earth caused by dynamic thinning using three Greenland GNSS Network (GNET) stations located near the glacier termini. When we compared our results with discharge, we found a time lag between the onset of dynamic thinning/thickening and glacier speedup/slowdown. Our results showed that dynamic thinning on Jakobshavn Isbræ occur 0.87 ±0.07 years before speedup. This implies that the GNSS time series can be used to predict speedup/slowdown of Jakobshavn Isbræ by up to 10.4 months. For Kangerlussuaq and Helheim the thinning occur 0.37 ±0.17 years (4.4 months) and 0.03 ±0.16 years (11 days) before speed up, respectively. In the second study, we used tenyear long records of Surface Elevation Change (SEC) derived from three GNSS ...