A new ice thickness and bedrock data set for the Greenland ice sheet

Ice thickness data collected between 1993 and 1999 using a coherent ice penetrating radar system developed at the University of Kansas have been combined with data collected by the Technical University of Denmark in the 1970s to produce a new ice thickness grid for Greenland. Cross-over analysis was used to assess the relative accuracy of the two data sets and they were weighted accordingly and interpolated onto a regular grid using an optimal interpolation procedure. A high resolution land-ice mask was used to help constrain the interpolation of the ice thickness near the ice sheet margins where, in the past, the relative errors have been largest. The ice thickness grid was combined with a new digital elevation model of the ice sheet and surrounding rock outcrops to produce a new bed elevation data set for the whole of Greenland. Relative measurements of the reflectivity of the bed/ice interface were extracted from the 1990s data to show areas of potential basal melting, a pre-requisite for basal sliding.