Active microwave measurements of snow cover progress in polarimetric SAR

In hydrological investigations, modeling and forecasting of snow melt runoff requires information about snowpack properties and their spatial variability. In particular, timely measurement of snow parameters is needed for operational hydrology. This paper reports the authors´ recent progress on deriving snow covered area and snow wetness by using the NASA/JPL airborne and SIR-C/X-SAR spaceborne polarimetric synthetic aperture radar (SAR) imagery. Mapping areas covered by wet snow in remote alpine regions by using single polarization SAR imagery requires topographic information to obtain correct radiometric measurements and to reduce angular dependence for discrimination. However, the mapping of wet snow by using measurements of the polarization properties from the polarimetric SAR does not require topographic information. The authors have developed and tested an algorithm for snow wetness retrieval using C-band polarimetric SAR imagery. Test results using JPL AIRSAR and SIR-C data show that the authors´ algorithms can be used to provide quantitative estimates of liquid water content in the top layer of a snowpack