Three-dimensional velocity variations due to ice mass changes in Greenland – Insights from a compressible glacial isostatic adjustment model

• Main Authors: Steffen, R., Steffen, H., Huang, P., Tarasov, L., Kjeldsen, K., Khan, S.
• Format: Conference Object
• Language: English
• Published: 2023
• Subjects: Greenland
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5016991

Glacial isostatic adjustment (GIA) models provide estimates for velocity, gravity and sea-level change based on ice loading scenarios of past glaciations. The input to GIA models is quite extensive and consists of ice histories and a variety of Earth model parameters that describe the three-dimensional (3D) structure and rheology. Here, we will show the effect of a range of lithospheric thickness models on vertical and horizontal velocities in Greenland using a 3D compressible GIA Earth model. The lithospheric thickness beneath and around Greenland varies from a few tens of kilometres in offshore regions to several tens of kilometres (up to 200 – 250 km) in land areas. However, to date, no one has done an analysis of the impact of lateral lithospheric variation on the 3D velocity field for Greenland as horizontal velocities from incompressible GIA models, which are commonly used, are not suitable to be used due to the neglect of material parameter changes related to the dilatation. Compressible GIA models in turn can provide more accurate estimates of the horizontal and vertical viscoelastic deformations induced by ice-mass changes. We use various lithosphere models as input into a new 3D compressible GIA model code, which is constructed with the finite-element software Abaqus. We apply recent ice history models Huy3 and GLAC-GR2a for Greenland in combination with a Little Ice Age deglaciation model. The modelled 3D velocity field is compared against independent GNSS (Global Navigation Satellite System) observations as well as to previously modelled estimates using incompressible 3D GIA models.