The present and future of using InSAR to estimate SWE

Abstract:

For a large population around the globe, the accurate assessment of snow water equivalent (SWE) is crucial in estimating spring runoff as it relates to water resource management, flood hazard mitigation, drought monitoring, and climate change impacts. Despite some success in focused studies over a single watershed, a reliable cost effective remote sensing method to estimate SWE over large geographic areas still eludes the snow hydrology community. Investigations into using interferometric synthetic aperture radar (InSAR) to estimate snow water equivalent have yielded promising results. The InSAR method leverages the fact that at relatively low frequencies (L- and C-Band) differences in snow microstructure and layering do not significantly affect the radar backscatter of dry snow. At these frequencies, the main contribution of the radar backscatter is the snow/ground interface, and the difference in the timing of the radar propagation through the snowpack is related to the interferometric phase shift between acquisitions. Moreover, sensitivity of the InSAR SWE technique to density and number of layers appears to be low. Existing and future platforms both from air and space show potential of multi-temporal interferometric collections to track the evolution of the snowpack over an entire winter season. In the past, availability of InSAR data has been difficult for regions around the globe and during the winter seasons where the technique can be explored. Results from existing InSAR platforms will be presented as well as (and perhaps of more interest) the planned missions that hold the possibility of a dedicated InSAR platform with regular repeat coverage and no limitation on data distribution. Current airborne platforms with interferometric capabilities but with previous focus on glaciological, seismic, and soil moisture studies may also be considered for the application of InSAR estimation of SWE.