Elevation Change of Icelandic Glaciers from TanDEM‑X DEM Differencing with Penetration‑Bias‑Optimized Scene Selection

Mapping of elevation changes across large glacier regions is an essential basis for future IPCC reports. The first Glacier Mass Balance Intercomparison Exercise (GlaMBIE) established a community estimate of global glacier mass change [1]. However, the method of InSAR DEM differencing remains an underrepresented data source in this experiment.

For the second GlaMBIE data contribution, we aim to update our existing DEM Differencing processing pipeline [2]. It will be implemented on the high performance “Terrabyte” platform at the Earth Observation Center (EOC) of DLR. Unlike our previous contribution [2], which relied on targeted acquisitions to cover entire glacier regions, we will exploit the existing TanDEM‑X catalogue. This strategy facilitates future processing of large glacierized regions worldwide.

Recent advances regarding the uncertainty assessment of TanDEM-X DEM Differences will be fully incorporated in this pipeline [3, 4]. Special attention is given to reducing possible biases due to signal penetration. This bias is mitigated by differencing carefully selected TanDEM-X acquisitions from the same season with unchanged SAR geometry, reducing penetration differences between DEMs. Moreover, the relative importance of SAR signal penetration for accurate mass balance measurements also reduces with the length of the observation period.

In this work we will calculate the elevation change of all glacierized regions in Iceland based on available acquisitions in the TanDEM-X catalogue. Because the majority of TanDEM-X data were originally tasked and intended for the TanDEM-X Global DEMs, the final coverage will naturally gravitate towards these acquisitions, however alternative more suitable scenes in the catalogue will be substituted. A penetration-bias-optimized coverage for Iceland is best achieved by targeting the 2013 - 2021 period, with replacement scenes from other times possible.

We will investigate several spatial and temporal extrapolation strategies to fill gaps in Icelandic glacier coverage that must be left intentionally without measurements because the only available scenes are suspected of being affected by signal‑penetration biases.

References

[1]        Zemp, M., Jakob, L., Dussaillant, I., Nussbaumer, S. U., Gourmelen, N., Dubber, S., A, G., Abdullahi, S., Andreassen, L. M., Berthier, E., Bhattacharya, A., Blazquez, A., Boehm Vock, L. F., Bolch, T., Box, J., Braun, M. H., Brun, F., Cicero, E., Colgan, W., … The GlaMBIE Team. (2025). Community estimate of global glacier mass changes from 2000 to 2023. Nature, 1–7. https://doi.org/10.1038/s41586-024-08545-z

[2]        Abdel Jaber, W., Rott, H., Floricioiu, D., Wuite, J., & Miranda, N. (2019). Heterogeneous spatial and temporal pattern of surface elevation change and mass balance of the Patagonian ice fields between 2000 and 2016. The Cryosphere, 13(9), 2511–2535. https://doi.org/10.5194/tc-13-2511-2019

[3]        Hugonnet, R., Brun, F., Berthier, E., Dehecq, A., Mannerfelt, E. S., Eckert, N., & Farinotti, D. (2022). Uncertainty Analysis of Digital Elevation Models by Spatial Inference From Stable Terrain. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 15, 6456–6472. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. https://doi.org/10.1109/JSTARS.2022.3188922

[4]        Li, S., & Hajnsek, I. (2025). Geodetic glacier mass balance in the Karakoram (2011–2019) from TanDEM-X: An InSAR DEM differencing framework. Remote Sensing of Environment, 331, 115023. https://doi.org/10.1016/j.rse.2025.115023