Snow Depth Variability in the Northern Hemisphere Mountains Observed From Space
Accurate snow depth observations are critical to assess water resources. More than a billion people rely on water from snow, most of which originates in the Northern Hemisphere mountain ranges. Yet, remote sensing observations of mountain snow depth are still lacking at the large scale.
The referenced paper, Lievens et al. (2019), reports a promising new technique for estimating snow depth in mountains using C-band (5.4 GHz) synthetic aperture radar (SAR) observations from ESA's Sentinel-1 satellites. The method relies on both the cross-polarization and co-polarization backscatter observations, as well as time-series information.
An evaluation with in situ measurements from ~4000 sites and NASA MERRA-2 reanalysis data demonstrates that the Sentinel-1 snow depth retrievals capture the spatial variability between and within mountain ranges, as well as their interannual differences. With the 1-km resolution and regular, wide-area coverage of the snow depth estimates, plus ESA’s plans for continuing such observations into the 2030s, the new method could be a major component of a global snow depth and snow water equivalent (SWE) observing system — especially if combined with other techniques, including passive microwaves, that are more suitable for areas with shallower snow depths.
The novel 1-km resolution snow depth product enables snow studies in complex and inaccessible terrain where in situ measurements are sparse and where other spaceborne methods or model-based data products often have large uncertainties.
Abbreviations:
ESA: European Space Agency
MERRA-2: Modern-Era Retrospective Analysis for Research and Applications, Version 2
SAR: Synthetic Aperture Radar
Reference:
Lievens, H., M. Demuzere, H.-P. Marshall, R. H. Reichle, and Coauthors (2019), Snow depth variability in the Northern Hemisphere mountains observed from space, Nature Communications, 10, 4629, doi:10.1038/s41467-019-12566-y.
