Relating GNSS Reflected Signal Coherence to Ice Shelf Surface Deformation and Roughness

This study demonstrates the utility of the Global Navigation Satellite System Reflectometry (GNSS-R) method for remote sensing of ice shelf surface deformation and roughness. The phase coherence of the reflected GNSS carrier signal is related to surface deformation and roughness: smoother, less deformed areas scatter the signal more coherently. More than 900000 tracks of Spire Global Inc. grazing angle GNSS-R data collected over Antarctica between 2021 and 2023 were processed to determine signal carrier phase coherence. Results are presented in the form of coherence maps, where each measurement has a spatial resolution of approximately five kilometers, and the Ross Ice Shelf (RIS) is used as a case study for more detailed examination. Clear visual patterns in signal coherence are shown to correspond with the locations of streaklines and deformation features on the surface. A GNSS-R coherence-based roughness proxy is introduced and shown to correlate with surface roughness derived from the reference elevation model of Antarctica digital elevation model (REMA DEM). This novel application of the GNSS-R method demonstrates the exciting potential to complement existing data sources and improve understanding of ice shelf structure and evolution.