Speaker
Description
Ice loss from melting glacier and ice sheets is the dominant driver of sea-level change. To better estimate essential climate variables such as sea-level rise, synthetic aperture radar (SAR) observations can help us to understand the internal structures of ice masses while constraining and advancing models of ice-sheet and glacier mass loss. Polarimetric and interferometric SAR can differentiate and potentially locate subsurface interfaces, such as snow/firn/ice boundaries, as well as volumetric features including ice lenses and pipes within firn [1], [2], [3]. Together these individual components allow us to identify changes in glacier facies and characterize the internal composition of glaciers and ice sheets.
While current spaceborne SAR missions operate in a monostatic mode, bistatic and multistatic SAR introduce additional observation geometries that offer the potential to resolve subsurface properties that remain ambiguous in monostatic observations. By observing the same target from different transmitter-receiver geometries, systems such as the upcoming Harmony mission [4] may provide new sensitivity to polarimetric (bistatic) scattering mechanisms, e.g., the orientation of scatterers within a glacier and their incidence angle dependence. Simply observing the same snow, firn, and ice volumes at the same time from significantly different angles, already opens up enhanced sensitivity to refraction, and thus permittivity, effects [5].
Particularly the polarimetry of bistatic scattering from snow and ice is not yet well understood and brings new challenges: For example, changes in the propagation path and viewing geometry may complicate the estimation of the penetration bias essential to height change estimation [6]. Our understanding and appropriate usage of polarization information may differ not only from the conventional, monostatic H and V polarization basis, but also from solely considering bistatic surface scattering [7].
This poster reviews polarimetric scattering mechanisms and existing models observed in glacier and ice-sheet environments using monostatic SAR and discusses how these mechanisms may change under bistatic geometries. We identify challenges that must be addressed to properly interpret these measurements while identifying potential scattering features that could be resolved through the new observation geometries.
[1] E. Rignot, “Backscatter model for the unusual radar properties of the Greenland Ice Sheet,” J. Geophys. Res., vol. 100, no. E5, Art. no. E5, 1995, doi: 10.1029/95JE00485.
[2] G. Parrella, I. Hajnsek, and K. P. Papathanassiou, “Model-Based Interpretation of PolSAR Data for the Characterization of Glacier Zones in Greenland,” IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens., vol. 14, pp. 11593–11607, 2021, doi: 10.1109/JSTARS.2021.3126069.
[3] G. Fischer, K. P. Papathanassiou, and I. Hajnsek, “Modeling Multifrequency Pol-InSAR Data From the Percolation Zone of the Greenland Ice Sheet,” IEEE Trans. Geosci. Remote Sens., vol. 57, no. 4, Art. no. 4, Apr. 2019, doi: 10.1109/TGRS.2018.2870301.
[4] A. Kääb et al., “Potential of the Bi-Static SAR Satellite Companion Mission Harmony for Land-Ice Observations,” Remote Sens., vol. 16, no. 16, p. 2918, Aug. 2024, doi: 10.3390/rs16162918.
[5] A. Benedikter et al., “Toward Dry Snow Parameter Estimation by Simultaneous Multiple Squint Differential InSAR,” IEEE Trans. Geosci. Remote Sens., vol. 62, pp. 1–15, 2024, doi: 10.1109/TGRS.2024.3486328.
[6] G. Fischer, K. Belinska, A. Benedikter, K. Papathanassiou, I. Hajnsek, H. Rott, T. Nagler, and P. Prats-Iraola, "Bistatic Signal Penetration Geometry over Land Ice for the Harmony Mission," in Proc. Eur. Conf. Synth. Apert. Radar (EUSAR), Baden-Baden, Germany, 2026.
[7] L. Iannini, D. Comite, N. Pierdicca, and P. Lopez-Dekker, “Rough-Surface Polarimetry in Companion SAR Missions,” IEEE Trans. Geosci. Remote Sens., vol. 60, pp. 1–15, 2022, doi: 10.1109/TGRS.2022.3166124.