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Radar Polarimetric Observations Of A Tree Canopy

This paper introduces an effective technique for characterizing the propagation properties of a forest canopy. The technique requires the use of a polarimetric scatterometer, which is a calibrated radar capable of measuring the complete backscattering matrix (amplitude and phase) of the Scene it illuminates. A truck-mounted 1.6 GHz polarimetric scatterometer was used from a 19 m high platform to measure the backscattering from a dense canopy of pine trees at an incidence angle of 40". Two sets of measurements were made at each of many spatial locations, one set with and the other without a trihedral comer reflector present on the ground surface undemeath the canopy. From the two sets of polarimetric measurements, it was possible to determine the mean values and the statistical distributions of the canopy attenuation factors for horizontal and vertical polarizations. The mean values of the one-way attenuation factors were found to be 9.31 dB for horizontal polarization and 9.16 dB for vertical polarization.