Multi-stand radar modeling from a boreal forest: Results from the BOREAS Intensive Field Campaign-1993

A Boreal Ecosystem Atmosphere Study (BOREAS) Intensive Field Campaign was conducted in August 1993 to study portions of the Canadian boreal forest. The overall project has a strong remote sensing and modeling component to assess and monitor important ecosystem attributes as they relate to carbon, water and energy fluxes. The objective of the work is to assess the capabilities of multi-frequency and multi-polarization synthetic aperture radar (SAR) to remotely sense forest stands of different species and age. NASA/JPL´s airborne SAR was flown over forested areas reasonably pure stands of old and young aspen (broad-leaf) and jack pine (needle-leaf) trees. Ground truth, stand characteristics and tree architecture data were collected over the period of the experiment from four stands (one stand for each species and age type). L and C-band portable dielectric probes were used to measure the dielectric properties of the trees. The model parameters of each stand have been derived from this data set. They have been used in the GWU vegetation model to compute the backscattering coefficients. At L-band, model calculations show that large HH backscatter from the old jack pine stand is due to double bounce scattering from tree trunks while VV backscatter arises from direct backscatter from the tree canopy. It is also observed that L-band like and cross polarization ratios tracked biomass for old and young jack pine stands. These findings have been confirmed by comparison with AIRSAR data