Using repeat-pass SAR interferometry for mapping wet snowcovers

The capability of mapping wet snowcovers by means of SAR is well known. However, using only the backscattering intensity at C-band there still remain some incertitudes regarding the effect of either rough snow surfaces or very small liquid water contents for measurements performed at small incidence angles. Since the ERS satellites usually operate at 23° incidence angle, it is important to consider these effects. The authors show 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. In the situations examined the occurrence of wet snow could not be directly observed by means of the backscattering intensity, but the use of the degree of coherence allowed an easy discrimination. The results are validated with in-situ measurements and meteorological information