Multi frequency investigation of backscatter mechanisms within maritime glaciers

A detailed glaciological study using GPR will be carried out with emphasis on a multi-frequency system operating at a L-, C-, and Ku-band. This will allow features within the upper layers of the glacier which contribute to the backscatter signal received by satellite borne SAR sensors to be determined.

The amount the radar signal penetrates into snow, ice and firn depends on the frequency of the transmitted EM wave (Brenner et al. 2007),(Dall et al. 2001). C-band (5.3 GHz) has been the common frequency for Synthetic Aperture Radars (SAR) (including ERS-1/-2, RADARSAT, ENVISAT), although X-band (9.6 GHz) is used on TerraSAR-X and L-band (1270 MHz) on ALOS. Ku-band (13.5 GHz) is standard for radar altimeters (including RA-2, Jason1/2 and the upcoming CryoSAT2), but dual frequencies are common for recent and upcoming missions. This range of frequencies has improved interpretation capabilities for different targets due to the variable depth penetration of the signals (e.g. crevasse detection (Lacroix et al. 2007)).
The uncertainty in depth penetration at all of these frequencies for complex media means that we are still unsure what physical attributes of the glacier are contributing to the backscattered signal. Present and future missions are looking to exploit the increased information available from different frequencies and full polarization to improve data interpretation. Ground truthing data will play an essential role in understanding the scattering mechanisms responsible for the satellite signal.

In this project we propose to use a ground penetrating radar (GPR) operating at a number of different centre frequencies, common to satellite born radars, to provide this ground truthing component. The data will provide important insights into the frequency dependent interactions of EM waves in the snow, ice and firn of maritime arctic glaciers. These are expected to be very different from the much discussed larger ice masses of Antarctica and Greenland.