Complex evolving elevation change pattern of Jakobshavn Isbræ during 2003-2023

The surface elevation of the Greenland Ice Sheet undergoes continuous changes driven by the interaction of surface mass balance processes and ice dynamics, each displaying distinct spatial and temporal characteristics. In this study, we utilize satellite and airborne altimetry data with high spatial (1 km) and temporal (monthly) resolution to examine these changes from January 2003 to August 2023. Our analysis highlights the complex and evolving elevation change patterns of Jakobshavn Isbræ (JI). Specifically, we document thinning near the JI terminus from 2003 to 2015, followed by thickening of approximately 25 meters between 2015 and 2018, thinning of around 20 meters from 2018 to 2022, and slight thickening during 2022–2023.

To validate these findings, we compare surface elevation changes derived from satellite and airborne altimetry with GPS observations from bedrock-based monitoring stations near the JI margins. These GPS stations capture bedrock displacement due to ongoing land uplift in response to current ice mass changes, with the glacial isostatic adjustment (GIA) signal removed. The GPS data, providing continuous daily estimates of mass changes, corroborates the intricate and evolving elevation change patterns observed in JI.