UAV’s to monitor the mass balance of glaciers

Uncrewed Aerial Vehicles (UAVs) are increasingly employed for glacier monitoring, particularly for small to medium-sized glaciers. The UAVs are mainly used to generate high-resolution Digital Elevation Models (DEMs), delineate glacier areas, determine surface velocities, and map supraglacial features. In this study, we utilise UAVs across various sites in the Alps and the Tien Shan (Central Asia) to monitor the mass balance of glaciers. We present a workflow for calculating the annual geodetic mass balance and obtaining the surface mass balance using the continuity-equation method. Our results demonstrate generally a close alignment between the determined mass balances and those obtained through traditional glaciological methods involving intensive fieldwork. We show that utilising UAV data reveals significantly more spatial details, such as the influence of debris and collapsing ice caves, which are challenging to capture using conventional methods that strongly rely on interpolation and extrapolation. This underscores the UAV's significance as a valuable add-on tool for quantifying annual glacier mass balance and validating glaciological assessments. Drawing on our experience in on-site UAV glacier surveys, we discuss the methodology's advantages, disadvantages, and potential pitfalls.