UAV-based monitoring of the mountain cryosphere: Recent advances and future prospects

The mountain cryosphere responds very sensitively to global climate change because of local processes and positive feedbacks, with far-reaching hydrological, ecological and socio-economic consequences at different spatial scales. To uncover rapid changes, assess potential impacts and develop effective adaptation strategies, comprehensive monitoring of the state and evolution of the mountain cryosphere is essential. In recent years, unoccupied aerial vehicles (UAVs) equipped with cameras or geophysical and meteorological instruments have been increasingly deployed for detailed mapping and monitoring of the mountain cryosphere. UAVs facilitate a wide range of geoscientific applications and are particularly useful for surveying areas in alpine terrain that are difficult to access. They also have great potential for the spatial study of small-scale and dynamic processes. Using high-resolution digital elevation models or dense point clouds from (repeated) UAV surveys has become a widespread method for mapping snow depth changes and quantifying glacier volume loss. The ongoing miniaturisation of electronic sensors and the specific development of multispectral and thermal infrared cameras, GPR and LiDAR systems and other geophysical instruments for UAV-based surveys have opened up new opportunities for cryospheric research in complex terrain. Recent advances include the measurement of glacier thickness and snow depth using UAV-borne GPR, the mapping of supraglacial debris thickness and permafrost distribution using UAV-based thermal infrared thermography, the mapping of snow and ice albedo using UAV-based multispectral imaging, and the investigation of the atmospheric boundary layer over ice and snow using UAVs. Here I briefly discuss the potential and limitations of recent advances in UAV technology for cryospheric research and outline future prospects for the detailed monitoring of mountain glaciers, permafrost and snow cover.