Interpretation of amplitude data from a ground-based radar in combination with terrestrial photogrammetry and visual observations for calving monitoring of Kronebreen, Svalbard

Abstract

A ground-based radar has been used successfully for monitoring calving events and velocities at Kronebreen, Svalbard, for two test seasons in 2007 and 2008. We use daily terrestrial optical photogrammetry and continuous visual observation to validate the interpretation of a 116 hour groundbased radar amplitude of return signal data recorded from 26 to 30 August 2008. The radar was placed ∼4 km from the glacier. It measured at high temporal rate (2 Hz) and the antenna lobe covered a width of ∼700 m of the front. The calving-front geometry was extracted from the optical images, and its effect on radar backscatter, together with the movement of the glacier, was identified in the plot of the amplitude of the radar return signal. Calving events were detected applying an automated change-detection technique to the radar dataset. This technique allowed us to detect 92% of the events that were observed during the same time. In this paper, we focus on the method rather than on data interpretation. However, future use of this method, combined with meteorological data, tides and ocean temperature, will be valuable for calving-process studies.