Long-term Autonomous Tidewater Glacier Monitoring Using a Long-Range Terrestrial LiDAR Scanner; Helheim Glacier, Southeast Greenland

Abstract:

Tidewater glaciers exhibit dynamic behaviors across a range of spatial and temporal scales, posing a challenge to both in situ and remote sensing observational strategies. In situ measurements can capture variability over very short time intervals, but with limited spatial coverage and at significant cost and risk to deploy. Conversely, airborne and satellite remote sensing is capable of measuring changes over large spatial extents but at limited temporal sampling. In recent work, we have shown that long-range Terrestrial LiDAR Scanning (TLS) from fixed near-situ locations is capable of combining the rapid acquisition capabilities of in situ measurements with the broad spatial coverage of traditional remote sensing. LiDAR scanners have typically operated for short-duration campaigns (days to weeks) due to the technical complexity of the instrumentation, which has limited their contribution to tidewater glacier studies to “snapshot” observational datasets.

This paper describes the development and deployment an autonomous full-waveform, long range (6-10 km) TLS system for extended operation (> 1 year) in a remote Arctic environment. The instrument uses a 1064μm wavelength laser which has been optimized for snow and ice, and allows us to acquire multi-dimensional point-cloud measurements of the lower reaches of the glacier, its terminus and the mélange to distances in excess of 10 km every few hours. The system was deployed at Helheim Glacier, southeast Greenland in late July, 2015. Helheim Glacier is a large tidewater outlet glacier of the Greenland Ice Sheet and the focus of a coordinated interdisciplinary program to study of its dynamics and interaction with the ocean. Results from our year-round scanning instrument will provide new insights into short and long-term ice motion and terminus behavior at temporal and spatial resolutions previously not possible.