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

Measuring glacier elevation change is crucial informationfor estimating glacier mass balance, calibrating massbalance and climate models, and assessing the impact of globalwarming. We examined the potentiality of clinometry to quantifyglacier elevation changes. This technique allows calculating theelevation of the points that lie on the margins of the shadows castby the local topography on monoscopic optical images. Mappingthe shadow position across different images permits quantifyingsurface elevation changes. We applied clinometry to Sentinel-2images of the Aletsch Glacier (Switzerland) and we measureda glacier thinning of -1.9 ± 1.7 ma-1 between 2017 and 2021,in agreement with previous observations.