A large scale microwave emission model for forests. Contribution to the
SMOS algorithm

R. Rahmoune, A. Della Vecchia, P. Ferrazzoli, L. Guerriero, and F. Martin-Porqueras

Abstract

The SMOS mission will provide soil moisture and ocean salinity at global scale. The principle for soil moisture monitoring is the high sensitivity of L-band measurements to surface soil water content. Since a significant percentage of pixels contains arboreous vegetation (at least partially), a reliable estimate of forest emissivity is needed to fully exploit the potential of the mission. Moreover, soil moisture can be retrieved in areas with sparse woodland, but this requires a detailed knowledge of the variables which affect the overall emissivity. To effectively manage these problems, the electromagnetic model developed at Tor Vergata University was combined with information available from forest literature. Using allometric equations and auxiliary information, the geometric and dielectric inputs required by the model were related to global variables available at large scale, such as Leaf Area Index. Different distributions of trunk diameters are being considered. Simulations indicate that, at L-band, leaves are almost transparent, attenuation is mostly due to branches, and soil contribution can be still appreciable, unless the forest is dense. The model is being refined, to consider seasonal variations of foliage cover, subdivided into arboreous foliage and understory contribution.

Index Terms—Microwave emission. Forest. SMOS algorithm. AMIRAS

European Geosciences Union General Assembly 2009, Vienna, Austria, 19 – 24 April 2009

Geophysical Research Abstracts, Vol. 11, EGU2009-5218, 2009

© Authors, 2009

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