Conference Agenda

Ice mapping is one of the secondary objectives of ESA's fully polarimetric P-band SAR mission, BIOMASS, recently launched on 29 April 2025 [1]. The use of P-band allows for deeper penetration into ice sheets and glaciers than what has been possible with the higher frequency spaceborne systems, used until now. The BIOMASS mission potentially allows for the mapping of subsurface features such as ice inclusions in the firn-pack, aquifers, and firn depths though the employment of advanced SAR techniques, namely Polarimetric SAR Interferometry (PolInSAR) and SAR Tomography (TomoSAR). Over the course of the BIOMASS mission, data will be acquired in two acquisition phases with orbits designed specifically for each of the two techniques. Furthermore, during the BIOMASS commissioning (COM) phase, data will be gathered with large spatial baselines over the Antarctic continent, potentially allowing for TomoSAR mapping of ice sheets with high vertical resolution.

From 11 December 2023 to 14 February, the Technical University of Denmark completed an airborne radar campaign in Antarctica. The primary objective was to gather airborne P-band data from the Antarctic continent in support of BIOMASS. Data was acquired with the POLARIS instrument, which was developed by the university, and commissioned by ESA [2]. The POLARIS instrument is a fully polarimetric P-band radar capable of operating both as an ice sounder and in a SAR configuration. During the campaign, PolInSAR data was acquired around the Dome C region in the dry snow zone, where no summer melt occurs. Also, both PolInSAR, TomoSAR, and ice sounder data was acquired at the Shackleton ice shelf in the percolation zone, where summer melt percolates down through the firn-pack, thus forming ice inclusions.

Previously, PolInSAR and TomoSAR analyses of ice sheets have been carried out in Greenland. However, this was in the ablation and percolation zone [3][4][5]. However, 90% of the Antarctic ice sheet is in the dry snow zone. Furthermore, the Antarctic continent is subject to specific meteorological conditions, which are not present in other snow-covered regions. Most notably, the surface at the Dome C region is dominated by longitudinal snow dunes [6]. These surface features lead to highly anisotropic backscatter while also potentially impacting the polarimetric signature of SAR images [7].

In this contribution, we present polarimetric analysis and PolInSAR results for both sites based the Uniform Volume under Surface (UVuS) model [8] (Dome C) and a more complex coherence model, accounting for both a surface and a subsurface scattering layer [3] (Shackleton). Furthermore, the presence of both PolInSAR, TomoSAR, and ice sounder data at the Shackleton site allows for a very thorough assessment of the feasibility of subsurface mapping of ice sheets through PolInSAR and TomoSAR techniques. At this site, subsurface structures observable in TomoSAR and ice sounder profile was predicted by PolInSAR model inversion, signifying an excellent level of cohesion between techniques. Finally, degradation of airborne P-band data allows for the direct assessment of BIOMASS feasibility regarding the subsurface mapping of ice sheets through the employment of TomoSAR and PolInSAR techniques.

References

[1] Shaun Quegan et al. “The European Space Agency BIOMASS mission: Measuring forest above-

ground biomass from space”. eng. In: Remote Sensing of Environment 227 (2019), pp. 44–60. ISSN:

18790704, 00344257. DOI: 10.1016/j.rse.2019.03.032.

[2] Jørgen Dall et al. “ESA’S POLarimetric Airborne Radar Ice Sounder (POLARIS): design and first

results”. eng. In: I E T Radar, Sonar and Navigation 4.3 (2010), pp. 488–496. ISSN: 17518784,

17518792. DOI: 10.1049/iet-rsn.2009.0035.

[3] Georg Fischer, Konstantinos P Papathanassiou, and Irena Hajnsek. “Modeling multifrequency pol-

InSAR data from the percolation zone of the Greenland ice sheet”. In: IEEE Trans. Geosci. Remote

Sens. 57.4 (Apr. 2019), pp. 1963–1976.

[4] Georg Fischer et al. “Modeling the Vertical Backscattering Distribution in the Percolation Zone of

the Greenland Ice Sheet With SAR Tomography”. eng. In: Ieee Journal of Selected Topics in Applied

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DOI: 10.1109/JSTARS.2019.2951026.

[5] Francesco Banda, Jørgen Dall, and Stefano Tebaldini. “Single and multipolarimetric P-band SAR

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pp. 2832–2845.

[6] Marine Poizat et al. “Widespread longitudinal snow dunes in Antarctica shaped by sintering”. en. In:

Nat. Geosci. 17.9 (Sept. 2024), pp. 889–895.

[7] Jayanti J Sharma et al. “Polarimetric decomposition over glacier ice using long-wavelength airborne

PolSAR”. In: IEEE Trans. Geosci. Remote Sens. 49.1 (Jan. 2011), pp. 519–535.

[8] Jørgen Dall, Konstantinos Papathanassiou, and Henning Skriver. “Polarimetric SAR interferometry

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