Abstract
Abstract. This study presents the detailed survey of the northern marginal part of Russell Glacier, SW Greenland using the combination of unmanned aerial vehicle (UAV) photogrammetry and low-frequency ground penetrating radar (GPR) measurements. Obtained digital elevation model (DEM) and ice thickness data from GPR data allowed the generation of high precision subglacial topography model. We report uncertainties arising from GPR, GPS, and DEM suggesting sufficient accuracy for the reconstruction of glacier bed topography. GPR data and generated subglacial topography model does not reveal any possible Nye channel that could be incised into the bedrock, however, we were able to detect englacial tunnel that runs approximately parallel to the ice margin and possibly is a remnant of a tunnel that provided passage for ice-dammed lake waters during the latest jökulhlaups (2007, 2008). We also observe a radar-transparent layer up to 20 m from the glacier surface suggesting the boundary of cold/temperate ice or piezometric surface. The latter one is preferred due to the warm climatic conditions which are supposed to warm up possible winter cold wave.
Highlights
Lamsters et al (2016) demonstrated that an accurate map of the subglacial topography can be generated using only GPS measurements of glacier surface combined with ice thickness data from Ground-penetrating radar (GPR), but it could be complicated if the ice surface is very articulated
Aerial survey with small and low-cost unmanned aerial vehicle (UAV) and groundpenetrating radar (GPR) measurements of the study area were performed on July 27 with the main task to generate digital elevation model (DEM), orthomosaic, subglacial topography and ice thickness maps
Our GPR data confirm that ice margin is definitely warm-based and that the surveyed part of the glacier is temperate
Summary
To obtain a precise model of subglacial topography, particular attention must be paid to the generation of precise DEM of the glacier surface. There are many ways, how the elevation of the glacier surface can be obtained, for example, interpolation of DEM from GPS points or DEMs derived from LiDAR data or photogrammetry. There are profits and downfalls for each method – poor resolution of the data (GPS point grid and global DEM models), high acquisition costs (LiDAR data acquisition), unsuitable weather conditions (photogrammetry and LiDAR data acquisition). Lamsters et al (2016) demonstrated that an accurate map of the subglacial topography can be generated using only GPS measurements of glacier surface combined with ice thickness data from GPR, but it could be complicated if the ice surface is very articulated. UAV photogrammetry has become an accurate tool in glaciology for the generation of high-precision DEMs (e.g. Ryan et al, 2015; Bhardwaj et al, 2016; Ely et al, 2017; Rossini et al, 2018; Ewertowski et al, 2019; Jouvet et al, 2019; Lamsters et al, 2019, 2020)
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