GNSS Reflectometry on the McMurdo Ice Shelf

Abstract. The ability to monitor glaciated surface types, including snow, ice and meltwater, at a high spatial resolution, is critical for monitoring overall glacier mass balance. Using an Antarctic ice shelf as a study site, we tested the feasibility of Global Navigation Satellite System reflectometry (GNSS-R) and GNSS interferometric reflectometry (GNSS-IR) in monitoring glacier surfaces. During the 2023–24 Antarctic austral summer, we conducted a field campaign to collect GNSS-R front-end samples from one 9-m tower and GNSS-IR samples from one 1.5-m tower offset 14 m away horizontally, at each of two sites located on the McMurdo Ice Shelf near McMurdo Station, Antarctica.  The towers near Phoenix airfield were on snow-covered ice.  The towers near McMurdo's former Pegasus airfield were on a heterogeneous surface of bare ice and snow-covered ice, which varied temporally.  From mid-November to early December 2023, we collected GNSS-R, GNSS-IR, camera imagery, and lidar data of the glacier surface within a 20 m radius at each of the two 9-m tower sites. All data were returned to the lab for post-processing.

We show our results processing the GNSS-R front-end samples to estimate the surface reflectivity from the signal-to-noise ratio.  We find that the GNSS-R signal-to-noise ratio is insufficiently strong for estimating surface reflectivity. We also show our results processing the Earthscope geodetic receiver data for interferometric reflectometry, looking at the spectral peak amplitude as the indicator of surface type. We find that the GNSS-IR spectral peak amplitude mean and bias differ between the two sites, but cannot rule out the role that hardware differences between the sites may have in this.