An analysis of L- and C-band boreal forest backscattering properties with r
espect to various temporally changing parameters is presented. The seasonal
and weather dependent parameters considered include the depth of soil fros
t, topsoil moisture, snow water equivalent, air temperature and precipitati
on. The effect of these parameters on sigma(o) are studied for various stei
n volume (biomass) classes by comparing the results against a cloud model-b
ased semi-empirical modeling approach. Semi-empirical modeling is also used
for a for est biomass retrieval experiment. The SAR data set includes 4 JE
RS-1 (L-band, HIT-polarization) and 19 ERS-1 (C-band, VV-polarization) imag
es for a test area in southern Finland, Additionally, a set of 2 JERS-1 and
3 ERS-1 images for another. test al ea in northern Finland is employed. Th
e results show that radar response to forest biomass is more sensitive to c
hanges in temporally varying parameters at C-band than at L-band. The semi-
empirical modeling approach describes well the behavior of sigma(o) at both
frequency bands when large forest areas are considered. Moreover, the mode
ling approach appeals to be applicable for different conifer-dominated bore
al for est types. Since the modeling approach explains satisfactorily the a
verage backscattering behavior, the results in biomass retrieval show high
accuracies (25-30% relative RMSE) when areas under investigation are large
enough, i.e, about 20 ha.