Measuring Glacier Elevation Change by Tracking Shadows on Satellite Monoscopic Optical Images

Measuring glacier elevation change is crucial information for estimating glacier mass balance, calibrating mass balance and climate models, and assessing the impact of global warming. We examined the potentiality of clinometry to quantify glacier elevation changes. This technique allows calculating the elevation of the points that lie on the margins of the shadows cast by the local topography on monoscopic optical images. Mapping the shadow position across different images permits quantifying surface elevation changes. We applied clinometry to Sentinel-2 images of the Aletsch Glacier (Switzerland) and we measured a glacier thinning of −1.9 ± 1.7 ma−1 between 2017 and 2021, in agreement with previous observations.