N. Baghdadi et al., Accuracy of wet snow mapping using simulated Radarsat backscattering coefficients from observed snow cover characteristics, INT J REMOT, 20(10), 1999, pp. 2049-2068
Wet snow cover mapping by means of airborne and spaceborne SAR is operation
al today and successfully applied in rugged high mountain terrain and in ag
ricultural area. This paper proposes a numerical study to estimate the accu
racy of wet snow mapping by using a radar backscattering model that simulat
es backscattering from a multi-layer snowpack for various snow cover condit
ions and for SAR parameters specific to Radarsat (C-HH). Field measurements
carried out in numerous sites during the winters of 1994 to 1996 in severa
l areas of Quebec (Canada) have allowed to choose some typical snow profile
s and the corresponding snow/soil parameters. Results indicate that under t
he assumptions used in the model and the simulations, for the standard mode
S1 of Radarsat (20 degrees to 27.4 degrees) and in the case of wet snow co
ver with liquid water content of 1%, the optimum relative under- and over-e
stimation of wet snow pixels are of the order of 23.9% and 13.4%, respectiv
ely. For wet snow cover at 2%, the algorithm operates with a relative under
-estimation of wet snow pixels around 8.5% and a relative over-estimation o
f the order of 1.7%. For wet snow with liquid water content of 4%, the rela
tive under- and over-estimation of wet snow pixels is around 0.8% and 0.3%,
respectively. They are negligible for wet snow with liquid water content h
igher than 4%. With the standard mode S7 of Radarsat (44.9 degrees to 49.4
degrees), the wet snow mapping algorithm leads to a slightly lower performa
nce than with the standard mode S1. The accuracy of the method for wet snow
mapping demonstrates the high potential of SAR for snow monitoring. It is
considered sufficient when the liquid water content of the snowpack is high
er than 1% for actual snow conditions similar to those eight observed condi
tions used in this study.