Sentinel-1 snow depth retrieval at sub-kilometer resolution over the European Alps

Summary

This study demonstrates that Sentinel-1 synthetic aperture radar can retrieve snow depth at sub-kilometre resolution over mountainous terrain by exploiting changes in radar backscatter during snow accumulation and ablation. Validation against 743 Alpine sites showed strong correlation (r = 0.89) at 500 m and 1 km resolutions for dry snow, with mean absolute error of 20–30% for snow depths between 1.5 and 3 m. The findings address a significant gap in high-resolution snow monitoring for mountain regions where conventional satellite methods are limited by topography, with applications to water resource management and flood forecasting.

Regional applicability

This study was conducted directly over the European Alps (Austria and Switzerland) and therefore has strong applicability to UK mountain regions, particularly Scotland, the Lake District, and Wales where seasonal snow monitoring could improve water resource and flood management. The methodology would require validation in British mountain terrain, which tends to have shallower snow accumulation and more frequent freeze–thaw cycles than the Alpine sites studied.

Key measures

Snow depth retrieval accuracy; spatio-temporal correlation (r = 0.89 at 500 m and 1 km); mean absolute error (20–30% of measured values); Sentinel-1 radar backscatter (cross-polarization); snow water equivalent (SWE)

Outcomes reported

The study evaluated Sentinel-1 synthetic aperture radar's ability to retrieve snow depth at sub-kilometre spatial resolutions (100 m, 500 m, 1 km) over the European Alps using an empirical change detection algorithm. Performance was validated against 743 in situ measurement sites across Austria and Switzerland.

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