Multiscale change detection in a supraglacial stream using surface drifters

Abstract

High-resolution (1 – 10 m) observations of supraglacial streams are needed to improve process understanding and inform low-resolution (25 – 100 m) remote sensing observations and numerical models. To address this, we built small (0.25 m diameter) satellite positioning drifters. The devices recorded the surface flow velocity, linear acceleration and magnetic field intensity along a 250 m supraglacial channel during the summer ablation period from 30.06 to 04.07.2019 at Austre Brøggerbreen, Svalbard. Cross correlation analysis was performed on channel-fitted coordinates. Multiscale change detection was carried out by increasing the averaging window of the time series data and the stream-wise spacing of the drifter’s planar coordinates. The locations of channel bends and step-risers were found to correspond to clearly defined changes in the streamwise cross correlations of the flow speed, magnetic field intensity magnitude and acceleration magnitude. The proposed drifter-based approach provides a simple method to collect and assess high-resolution satellite drifter data for multiscale planform change detection in supraglacial channels.