Mapping wet snowcovers with SAR interferometry

The capability of mapping wet snowcovers by means of Synthetic Aperture Rad ar (SAR) is well known. However, using only the backscattering intensity at C-band, there still remain some incertitudes regarding the effect of eithe r rough snow surfaces or very small liquid water contents for measurements performed at small incidence angles. Since the European remote sensing (ERS ) satellites usually operate at 23 degrees incidence angle, it is important to consider these effects. This paper shows that these difficulties can be overcome using repeat-pass SAR interferometry. ERS data over a part of the Netherlands and a part of Switzerland are used as illustrative examples. I n the situations examined the occurrence of wet snow could not be directly observed by means of the backscattering intensity, but the use of the degre e of coherence allowed an easy discrimination. The results are validated wi th in situ measurements.