Recent advances in theoretical studies of L-band active and passive remote sensing of forests

The synergy between active and passive observations is becoming an attractive subject, particularly stimulated by the SMAP program. This paper investigates the potential advantage of the synergy related to the decoupling between the influence of soil and vegetation variables. If both the emissivity e and the backscattering coefficient σ° are available, the ratio between σ° and the reflectivity 1-e can be computed. This ratio is scarcely influenced by soil moisture while, assuming soil roughness to be almost constant with time, the ratio is mostly influenced by vegetation biomass.