Cooperative Institute for Research in Environmental Sciences

Synthetic Aperture Radar Imaging of Ice-bed Interface and Radar Sounding of Fast-Flowing Glaciers

Prasad Gogineni

Center for Remote Sensing of Ice Sheets (CReSIS)
The University of Kansas
Lawrence, KS

Recent satellite observations indicate that several outlet glaciers in the southern part of the Greenland ice sheet have sped up considerably over the last few years. Also, parts of the West Antarctic Ice Sheet are reported to be thinning significantly. We need an improved knowledge of basal conditions for understanding the rapid changes and incorporating this knowledge into models. A Synthetic Aperture Radar (SAR) that images the ice-bed interface with fine resolution both in the cross- and along-track directions can be used for accurate determination of basal conditions. Information about the bed topography and thickness is also crucial to identifying causes for these changes and to modeling ice sheets’ response to a warming climate.

We designed and developed radars that can image the ice-bed interface, measure ice thickness and map internal layers simultaneously from both surface-based and airborne platforms. The surface-based radar operates over the frequency range of 120-300 MHz that can image the ice-bed interface over a swath of 1000 m or more on either side of the radar-carrying platform. We used this radar to collect data over a 6-km swath along a distance of about 30 km between GISP and GRIP core sites at summit camp during July 2005. We also operated on the same platform an ultra wideband radar that works over the frequency range of 500-2000 MHz to map near-surface internal layers. The results from these experiments showed, for the first time, that we could image the ice-bed interface through more than 3-km thick ice. In this paper, we provide a brief description of the system and experiments, and show sample results from data collected with our prototype radar.

We operated airborne radar with digital beam forming capability to sound Jakobshavn and other fast-flowing glaciers. We obtained ice thickness information across and along the channel up to the calving front of the Jakobshavn glacier for the first time with a radar.

In this talk, I will provide radar design considerations and results from surface-based and airborne experiments over the Greenland ice sheet. I will also provide a brief overview of the Center for Remote Sensing of Ice Sheets (CReSIS).

Prasad Gogineni