Advancing ice altimetry analysis to constrain the Antarctic Ice Sheet's response to climate change

• Applicants: Dr. Veit Helm, Ph.D., since 2/2021; Professor Dr.-Ing. Martin Horwath
• Subject Area: Geodesy, Photogrammetry, Remote Sensing, Geoinformatics, Cartography
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 442929109

The project shall exploit ice altimetry for a better understanding and quantification of the Antarctic Ice Sheet's responses to climate variability and climate change. Constraining these responses is urgently needed, e.g. for sea level projections. The potential of ice altimetry to contribute to this effort is growing and yet unexploited. We will process satellite radar altimetry measurements of past and present missions using advanced algorithms for topographic corrections and for mitigating firn penetration effects. We will combine these measurements with high resolution laser altimeter measurements of recent missions and produce time series of surface elevation changes. Our goal is to significantly reduce systematic errors as compared to previous processings and to arrive at a considerably better coverage at the ice sheet margins where previous algorithms failed.Subsequently, we will develop and apply innovative methods to analyse and interpret the altimetric surface elevation changes. The main processes that cause ice sheet elevation changes are an ice velocity out of balance and fluctuations in the firn layer at time scales from seasonal to centennial. We will explore the characteristic temporal and spatial patterns of each of these processes in order to develop a parametrization scheme that links altimetric surface elevation changes to the underlying processes. We will use this scheme to fill data gaps with physically realistic data and to reduce the effect of observation noise. The scheme will be further used to assign adequate densities to the different volume change effects and thereby to better constrain the ice mass balance. In contrast to previous studies, our approach is capable of dealing with ice and firn processes acting simultaneously, and therefore allows for physically consistent and realistic results. Through guiding the altimetry analysis by the current understanding of physical processing, the project will feed back to improvements of this understanding, that is, to improved modelling of ice flow dynamics, surface mass balance, and firn processes.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1158: Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas - with renewal proposal 2025 - 2030
• Ehemaliger Antragsteller: Dr.-Ing. Ludwig Schröder, until 2/2021