Midway evaluation in Geophysics - Jonas Liebsch

Event on Zoom

Title of thesis: Glacier evolution and glacial isostatic adjustment in Iceland

Student: Jonas Liebsch

Doctoral committee:
Guðfinna Aðalgeirsdóttir, Professor at the Faculty of Earth Sciences, University of Iceland
Eyjólfur Magnússon, Research Scientist at Institute of Earth Sciences, University of Iceland
Joaquín Munoz Cobo Belart, Geophysicist, Icelandic Institute of Natural History
Michelle Maree Parks, Geophysicist, Icelandic Met Office

Abstract

Integrating Altimetry and Snowpack Models to Refine SMB Estimates for Mýrdalsjökull Ice Cap Changes in glacial loading of the Mýrdalsjökull ice cap impact the dynamic behavior of the subglacial volcano Katla. Glacial changes since 2010 are quantified at daily resolution to improve understanding of Katla's response to both long-term and seasonal variations. Temporally sparse and irregular but precise satellite altimetry data (ArcticDEM, Pléiades, and ICESat-2) are integrated with temporally continuous surface mass balance estimates derived from the CARRA regional reanalysis (3-hour resolution).

First, CARRA is downscaled and used to force the energy balance and snowpack model COSIPY. Then, a novel statistical post-processing step is applied. It uses Bayesian linear regression to estimate and correct local scaling biases in modeled melt and precipitation, purely based on the observed elevation changes from DEMs.

Validation with in-situ measurements confirms that this approach significantly reduces local bias and adds substantial spatial detail to the coarse Regional Climate model input. Residuals from the correction process also prove useful for detecting anomalies in ice flow or melt due to geothermal heat flux. Additionally, the resulting bias maps reveal pronounced spatial variability in snow accumulation patterns driven by wind redistribution.