Conference Agenda

Microwave remote sensing has become an indispensable tool for monitoring polar regions, as its ability to penetrate dry snow and ice makes Synthetic Aperture Radar (SAR) particularly sensitive to subsurface structures. This sensitivity increases with decreasing frequency, enabling the detection of internal layers and features that remain invisible at higher frequencies.

ESA’s BIOMASS mission marks a significant milestone as the first spaceborne SAR system operating at P-band (435 MHz), providing unprecedented penetration depths and the potential to observe structural information from tens or even hundreds of meters below the surface [1]. Beyond its primary objective of global forest observation, BIOMASS offers new opportunities for cryospheric research through its fully polarimetric mode, which enables detailed characterization of scattering mechanisms within the Antarctic ice sheet.

This study focuses on an in-depth polarimetric analysis of BIOMASS data over Antarctica [2]. A dedicated test site will be selected based on the availability of ground reference measurements, such as sounder data, ground-penetrating radar (GPR) profiles, and ice core observations, which will be essential for validation and physical interpretation of the satellite data.

The analysis builds on previous experience with P-band SAR data in polar environments, gained during an airborne campaign with DLR’s F-SAR sensor in Greenland. There, multiple test sites across distinct glacial zones revealed key insights into polarimetric signatures. In the percolation zone, the anisotropic microstructure of the firn was shown to induce significant co-polar phase differences (CPD), and a corresponding CPD-based model established a quantitative relationship between polarimetric SAR measurements and firn thickness [3]. In the ablation zone, a Pauli decomposition in combination with entropy and the mean alpha angle distinguished areas with potential subtle differences in water content and density [4]. Furthermore, crevasses were effectively detected through characteristic combinations of volume and dihedral scattering, with polarization-dependent contrasts aiding their detection and characterization.

Preliminary investigations of BIOMASS P-band data indicate similar scattering mechanisms to those observed in the airborne campaign. However, several signatures identified in the BIOMASS polarimetry cannot yet be explained. To address this, the planned analysis will incorporate complementary decomposition techniques (e.g., eigenvalue-based and model-based approaches) to better characterize the dominant scattering mechanisms and retrieve their glaciological origin. A particular focus will be on investigating subsurface structures and exploring unusual scattering behaviors that may reveal previously unknown processes within the ice.

By integrating polarimetric analysis with reference data and advanced decomposition methods, this work aims to improve the physical understanding of P-band interactions with Antarctic ice. The resulting framework will provide the basis for fully exploiting BIOMASS P-band observations in cryospheric remote sensing and advancing the study of subsurface structures and ice-sheet dynamics.

[1] Rignot, E., et al. (2001). Penetration depth of interferometric synthetic-aperture radar signals in snow and ice. Geophysical Research Letters, 28(18), Art. no. 18.

[2] Cloude, S. (2010). Polarisation: applications in remote sensing (1st ed.). Oxford: Oxford University Press.

[3] Fischer, G. et al. (2019). Modeling Multifrequency Pol-InSAR Data from the Percolation Zone of the Greenland Ice Sheet. IEEE Transactions on Geoscience and Remote Sensing, Vol. 57, No. 4

[4] Schlenk, S. et al. (2025). Characterization of Ice Features in the Southwest Greenland Ablation Zone Using Multi-Modal SAR Data. The Cyrosphere