Estimation of moisture content of forest canopy from SAR data

During several field campaigns in spring and summer of ´94, the NASA/JPL airborne synthetic aperture radar (AIRSAR) collected data over the southern and northern study sites of BOREAS. Among the areas over which radar data were collected was the young jack pine (YJP) tower site, which is generally characterized as having short (2-1 m) but closely spaced trees with a dense crown layer. In this work, the authors use the AIRSAR data over this YJP stand from several different dates, and estimate the dielectric constant and hence the moisture content of its branch layer components. This is accomplished by applying a nonlinear estimation algorithm to the data assuming a parametric model of scattering derived from a discrete-component forest model. The results thus obtained show how the environmental conditions affected the moisture state of this forest stand over a period of six months. The results are compared to the available ground-truth measurements of moisture content and dielectric constant