Group activities and news

Open-source Python tool providing ice surface elevations and thickness along flux gates on the Greenland Ice Sheet now available

23 April 2026

In a newly published study in the GEUS Bulletin, researchers in our group presented PRODEM‑Xtract, an open‑source Python tool that delivers 32 m‑resolution annual ice surface elevations and thicknesses along Greenland Ice Sheet flux gates (2019–2024). Understanding how ice thickness evolves in these fast‑flowing marginal areas is essential for improving assessments of Greenland’s solid ice discharge, a key component of global sea‑level projections. The tool refines PRODEM elevations with high‑resolution ArcticDEM data and incorporates BedMachine v5 bed topography to produce detailed observations of annual ice thickness. Applied to major outlet glaciers – Sermeq Kujalleq, Helheim, and Kangerlussuaq – the PRODEM-Xtract tool reveals complex and previously unresolved dynamic thickness changes. By better resolving this spatial and temporal variability, we can significantly improve estimates of Greenland’s solid ice discharge and its year-to-year evolution.

Unprecedented observations of heterogeneity in the Greenland Ice Sheet firn layer

26 January 2026

Earlier this year, researchers from our group, collaborating with the Geological Survey of Denmark and Greenland (GEUS), published a new study in IEEE JSTARS (Journal of Selected Topics in Applied Earth Observations and Remote Sensing) looking at how the heterogeneity of the Greenland Ice Sheet firn layer has evolved through space and time. Firn (a transitional material between snow and ice) is incredibly important for buffering (i.e., slowing) sea-level rise as it allows for surface melt to be refrozen and stored internally instead of flowing off ice sheets and into oceans. For the first time, our research showed how the dynamic behaviour of this incredibly important part of the ice sheets can be observed directly from the synthesis of multiple satellite measurements (CryoSat-2, SARAL/AltiKa, SMOS). The results help chart a pathforward for new research in Earth Observation sensor fusion and the exciting types of novel observations we can make.

Exploration of multi-frequency satellite altimetry for snow depth estimates over sea ice in anticipation of CRISTAL

13 January 2026

In a study published today in The Cryosphere, led by researchers at the Arctic University in Tromsø (UiT) in collaboration with researchers from our group, University of Bristol, University College London, NASA and ESA, we explore the potential of estimating snow depth over sea ice with a dual-frequency approach using satellite laser and radar altimeters. Particularly, we use the combination of Ka-band and Ku-band radar altimetry to mimic the configuration of the future dual-frequency satellite CRISTAL, to be launched in 2027, and compare the observations with laser altimetry, to evaluate the penetration behaviour of Ka- and Ku-band observations. We observe stronger disagreements between expected surfaces in late winter, with potential biasing of up to 10 cm, with stronger dependency on multi-scale surface roughness rather than snow properties, as attributed in former studies. We also simulate expected radar observations of CRISTAL using its specific radar configurations, to provide critical insights into the potential of the CRISRAL mission to successfully achieve one of its primary objectives.

New studies examine snow depth retrieval methods over sea ice using multi-frequency air- and spaceborne altimetry

07 October 2022
Two recent publications in The Cryosphere present advancements in estimating snow depth over sea ice using multi-frequency altimetry, ahead of the European Space Agency's CRISTAL mission. In Part 1, researchers used data from an airborne campaign (CRYO2ICEANT22) utilising Ka-, Ku-, and C/S-band radars, along with a near-infrared lidar, to assess microwave penetration into the snowpack on Antarctic summer sea ice. The findings revealed that Ka- and Ku-band radars have limited penetration, with primary scattering occurring at the air–snow interface or within the snowpack, challenging traditional assumptions used in retrieval methodologies. Part 2 extended these observations by comparing the airborne estimates with near-coincident CryoSat-2 and ICESat-2 (CRYO2ICE), where it was shown that further work is required to validate such retrieval methods planned for CRISTAL, emulated by the CRYO2ICE data. 

Antarctica is undergoing ‘Greenlandification’

3 October 2025
A new Nature Geoscience study shows Antarctica is undergoing “greenlandification,” with ice loss processes similar to Greenland. DTU Space contributed key expertise from decades of satellite observations of Greenland’s ice, providing vital context for interpreting Antarctic change. As Senior Scientist Sebastian B. Simonsen notes, this knowledge transfer strengthens forecasts of sea level rise and supports future climate adaptation. Read more here.

Bias in modelled Greenland melt extent revealed by ASCAT satellite observations in a recent publication

12 August 2025
A new study pinpointing differences in regional climate model (RCM) melt extent using observations from the Advanced Scatterometer (ASCAT) is out! The paper was led by our PhD Student Anna Puggaard in collaboration with Senior Researcher Sebastian Simonsen and Professor Louise Sandberg Sørensen, as well as colleagues from DMI, GEUS, and ENVEO, where Anna also spent several months at ENVEO and GEUS on different research stays. Finally, this paper also marks the first publication of Anna's PhD! Interested? Read the publication here.

Senior Researcher Sebastian Bjerregaard Simonsen joins the EU Advisory Board for Destination Earth

8 August 2025
Destination Earth is an initiative to develop a digital twin of the planet to improve understanding and prediction of climate change and its impacts. The appointment recognises Sebastian Bjerregaard Simonsen's scientific expertise in climate modelling and Earth observation, placing DTU at the forefront of one of the EU’s most ambitious digital projects. Read more about this appointment in this news story. Sebastian is also the project science lead of the Digital Twin Ice Sheet project, which you can read more about here. 

Inaugural Lecture of Professor in Cryosphere Change, Louise Sandberg Sørensen

24 January 2025
Today, our group leader and newly appointed Professor Louise Sandberg Sørensen held her inaugural lecture. It was a captivating lecture on satellite stories of climate change in the cryosphere and her contributions to better understanding the mass balance of the Greenland ice sheet and its hydrology, which was followed up by a reception with colleagues, family, and friends.