Empirical Characterization of Surface Crevasse Clutter in Multi-Frequency Airborne Ice-Penetrating Radar Data

Orbital radar sounding systems could significantly improve our understanding of dynamic processes at ice sheet margins by enhancing the spatial and temporal coverage of subglacial observations. However, surface crevasses in these fast-flowing regions may contribute significant radar clutter that can impede detection of the ice sheet bed. It is currently unclear if particular radar center frequency choices might enhance or mitigate this clutter. To investigate this question, we analyze crevasse clutter returns in airborne radar sounding data collected at 195 MHz, 300 MHz, and 750 MHz. Additionally, we rescale the derived empirical angular scattering functions to simulate crevasse clutter in orbital geometries. In this data set, we find that, unlike rough surface clutter, crevasse clutter is reduced at higher frequencies. However, the small angles of incidence at orbital altitudes lead to sufficient clutter at all frequencies to dominate over the theoretical bed echo power. Our results suggest that surface crevassing may not necessarily limit the viability of UHF frequencies for orbital sounding. However, synthetic aperture focusing and narrow cross-track antenna beam patterns will be crucial regardless of system center frequency.