Geometric and Physical Constraints on Recovering Snow Covered Area from SAR

Snow covered area is an important variable in snowmelt runoff modelling. SAR can supply information on this parameter by detecting the decrease in the backscattering coefficient which occurs when the snowpack becomes wet. However, the method is subject to several geometric, geophysical and logistical constraints which limit its general applicability. These include missing coverage due to relief, reference image availability, inferring dry snow cover, validation and the sampling and time requirements for runoff modelling and forecasting. These are reviewed in this paper and where available, solutions are outlined along with their limits of applicability. Many of the topics discussed have relevance to other SAR applications.