First observations of sea ice flexural-gravity waves with ground-based radar interferometry in Utqiaġvik, Alaska

We investigate the application of ground-based radar interferometry for measuring flexural-gravity waves in sea ice. We deployed a GAMMA Portable Radar Interferometer (GPRI) on top of a grounded iceberg surrounded by landfast sea ice near Utqiaġvik, Alaska. The GPRI collected 238 acquisitions in stare mode during a period of moderate lateral ice motion during 23-24 April 2021. Individual 30 s interferograms exhibit ⼠20-50 s periodic motion indicative of propagating infragravity waves with ⼠1 mm amplitudes. Results include examples of onshore wave propagation at the speed predicted by the water depth and a possible edge wave along an ice discontinuity. Findings are supported through comparison with on-ice Ice Wave Rider (IWR) accelerometers and modeled wave propagation. These results suggest that the GPRI can be a valuable tool to track wave propagation through sea ice and possibly detect changes in such properties across variable ice conditions.