Glacier Melt detection via Satellite Radar in the Hindu Kush Himalaya

Lack of in situ monitoring stations at extreme elevations limits how scientists can understand when mountain glaciers melt and for how long. Here, we use over 32,000 Sentinel-1 synthetic aperture radar (SAR) images and a cloud computing platform to map glacier melt timing and duration over the entirety of the Hindu Kush Himalaya region (76,831 glaciers).

A disconcerting observation we made extends recent in situ observations from the Khumbu Glacier on Mount Everest that shows glacier melt is occurring at temperatures that never exceed -10ºC. Melt retrievals in our study show meltwater persistence for up to two months of the year at the highest glaciated elevations on earth (>7,000m a.s.l).

An critical assumption used to build “temperature indxed melt models” is that air temperatures greater than freezing drive glacier melt. Results from this study suggest this assumption must now be retired. Furthermore, we advance methods for a new generation of models that simulate glacier ablation based on the surface energy balance.

Retreival of melt status, extent, and duration from SAR time series provides an observational dataset necessary to develop real alternatives to temperature indexed melt models of glacier ablation.