Topography, ice thickness and ice volume of the glacier Pedersenbreen in Svalbard, using GPR and GPS

Abstract

Pedersenbreen is a small valley glacier (ca. 6 km2 in 2009), ending on land, located in north western Spitsbergen, Svalbard. Ground-based radio-echo sounding in April 2009, using a 100 MHzcommercial radar and a self-made low-frequency radar, revealed a polythermal structure. The radar was coupled with a global positioning system device to geo-reference the traces. Each radar profile was manually edited to pick the reflection arrival time from the interface between ice and bedrock. Travel times were converted to ice thickness using a velocity of 0.165 m/ns, which was estimated from common mid-point measurement. Then the surface topography, bedrock topography, ice thickness contours and ice volume were derived using interpolation methods. Because it was difficult to distinguish the reflection wave from the background with the 100-MHz radar in some of the thickest areas of Pedersenbreen, we used a 5-MHz radar of our own design to fill in this gap. The maximum thickness of Pedersenbreen reaches 183±9 m, and the ice volume is 0.393±0.047 km3 in 2009. Comparing these data with the surface topographical data available for 1936 indicates a mass loss of nearly 12% during the past 73 years. © 2014 S. Ai et al.