Observations of Radar Penetration into Snow on Sea Ice

• Main Author: Willatt, RC
• Other Authors: Laxon, SWC, Feltham, DL
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: UCL (University College London) 2012
• Subjects: Antarctic; Arctic; Canada; Antarc*; Antarctica; Climate change; Icebreaker; Sea ice
• Online Access: https://discovery.ucl.ac.uk/id/eprint/1370583/

Sea ice is an important indicator of climate change. The ability to measure sea ice thickness is essential for monitoring trends in the volume of Arctic and Antarctic sea ice. Several methods of determining sea ice thickness are presented and it is concluded that the most appropriate for studying sea ice thickness trends on long time- and length-scales is satellite radar altimetry. One key uncertainty associated with determining sea ice thickness using satellite radar altimetry is the penetration of the radar into the snow cover. We discuss the dielectric theory related to penetration into snow. The bandwidth of satellite radar altimeters is not sufficient to resolve the air/snow and snow/ice interfaces, or layers within the snow pack. For these reasons we investigate the radar penetration into snow on sea ice using sled- and air-borne radars with wide bandwidths so that the interfaces are resolved. Coincident field measurements of the physical snow characteristics were also gathered. Data from three studies are presented. The first study is an analysis of data from the UCL Ground Penetrating Radar (GPR) deployed from an icebreaker ship off the coast of Antarctica. The radar dominant scattering surface was the snow/ice interface for 30% of the snow pits. The second is an analysis of data from the Airborne Synthetic aperture and Interferometric Altimeter System (ASIRAS) off the coast of Arctic Canada. In 2006 the radar dominant scattering surface was closer to the snow/ice than air/snow interface for 25% of the echoes; in 2008, this was 60%. The third is an analysis of coincident GPR and ASIRAS data over Arctic sea ice. We found average radar penetration (P) of 0.29 for GPR and ASIRAS data at the South site. Retrieved sea ice thickness would increase by a factor of two with P=0.29 compared with P=1.