Radio echo sounding studies of Svalbard glaciers
The objective of this study was to investigate the radio echo sounding properties of Svalbard glaciers and to use these data to obtain information about the glaciological environment. Particular emphasis was placed on obtaining an understanding of the dielectric properties of the ice and reflecting boundaries present. These were then used to elucidate the physical processes causing them. First, a theoretical model, describing the dielectric properties of a wet bed, was developed. The ice/bed interface was then investigated using, as the primary data source, radar reflection coefficients. From these data inferences about the presence of water and/or debris, roughness of the interface and geographical trends were made. A number of geological divides were detected. Second, the dielectric properties of Svalbard ice were considered using i) radio echo sounding data on the bulk in situ radar absorption and ii) measurements made on the dielectric properties of a sample of Spitsbergen ice. Data were collected between 20 Hz and 100 kHz in the temperature range -2.5 to -44.0°C. From these and other data deductions about the thermal regime of the ice masses were made and a geographical trend, linked to the reflection coefficients, observed. The theory of dielectric absorption in ice was discussed with an emphasis on the high frequency, radio echo sounding characteristics. Third, the properties of an extraordinary internal reflecting horizon (observed on 60% of the glaciers sounded in 1983) were investigated. A model was developed to describe the scattering properties of inhomogeneities (of arbitrary size) within ice. Using this, and data on the reflecting properties of the horizons, they were attributed to the presence of a finite quantity of water. The implications of this finding were considered. Finally, the surface and, where available, bedrock profiles of 40 glaciers and six ice caps, in Spitsbergen, were presented.