This study presents the first subglacial topography and ice thickness models of the largest ice caps of the Argentine Islands, Wilhelm Archipelago, West Antarctica. During this study, ground-penetrating radar was used to map the thickness and inner structure of the ice caps. Digital surface models of all studied islands were created from aerial images obtained with a small-sized unmanned aerial vehicle and used for the construction of subglacial topography models. Ice caps of the Argentine Islands cover ~50% of the land surface of the islands on average. The maximum thickness of only two islands (Galindez and Skua) exceeds 30 m, while the average thickness of all islands is only ~5 m. The maximum ice thickness reaches 35.3 m on Galindez Island. The ice thickness and glacier distribution are mainly governed by prevailing wind direction from the north. This has created the prominent narrow ice ridges on Uruguay and Irizar islands, which are not supported by topographic obstacles, as well as the elongated shape of other ice caps. The subglacial topography of the ice caps is undulated and mainly dependent on the geological structure and composition of magmatic rocks.

This study presents the first high-resolution orthophoto maps and digital surface models (DSMs) of the largest Argentine Islands, West Antarctica. Aerial surveys with small unmanned aerial vehicle (UAV) were performed in Austral summer, 2018, taking 10,041 aerial photographs. Accuracy requirements were ensured using ground control points (GCPs). A resolution of 3.4 and 6.8 cm/px of orthomosaics and DSMs is reached on average, and the RMS reprojection error is 0.22 m on average. We report the morphometric parameters of surveyed islands and discuss issues related to accuracy and the usage of UAVs in polar conditions. This study demonstrates that small and low cost UAVs can be successfully used in harsh polar conditions to obtain accurate orthomosaics and DSMs of mainly glaciated terrain. We provide all generated materials in full resolution available in a scientific data repository that could be used for the monitoring of ice cap changes, vegetation cover, and wildlife populations.

Understanding glacier drainage system behaviour and its response to increased meltwater production faces several challenges in the High Arctic because many glaciers are transitioning from polythermal to almost entirely cold thermal structures. We, therefore, used ground-penetrating radar data to investigate the thermal structure and drainage system of Waldemarbreen in Svalbard: a small High Arctic glacier believed to be undergoing thermal change. We found that Waldemarbreen retains up to 80 m of temperate ice in its upper reaches, but this thickness most likely is a relict from the Little Ice Age when greater ice volumes were insulated from winter cooling and caused greater driving stresses. Since then, negative mass balance and firn loss have prevented latent heat release and allowed near-surface ice temperatures to cool in winter, thus reducing the thickness of the temperate ice. Numerous reflectors that can be traced up-glacier are interpreted as englacial channels formed by hydrofracturing in the crevassed upper region of the glacier. The alternative cut and closure mechanism of conduit initiation only forms conduits in parts of the lower ablation area. Consequently, Waldemarbreen provides evidence that hydrofracturing at higher elevations can play a major role in englacial water drainage through cold ice.

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.

No abstract