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The correct interpretation of SAR interferometric products such as single-/multipass coherence maps and interferograms requires an understanding of the different phenomena which may lead to the phase decorrelation of the backscattered signal. The specific aspect investigated in this work is the phase shift introduced by the change in soil moisture conditions. The goal was to get a preliminary evaluation of the magnitude of the phase shift for bare soil on dependence of the measurement parameters (frequency, polarisation, angle of incidence) in order to define a set of experiments to investigate the phenomenon, including the influence of surface roughness and soil type. The preliminary results show that: (i) in spite of the expected large change in power response when water is added to the sample, the signal remains generally well correlated; (ii) the coherent phase shift is clearly dependent on the moisture level of the upper soil layer but the shift versus total amount of added water quickly reaches saturation level; (iii) the dependence versus frequency is strongly modulated by the surface shape and by the incident angle.

Additional information

Authors: NESTI G, JRC Ispra (IT);TARCHI D, JRC Ispra (IT);RUDANT J P, Université Pierre et Marie Curie, Paris (FR)
Bibliographic Reference: Paper presented: IGARSS '95, Firenze (IT), July 10-14, 1995
Availability: Available from (1) as Paper EN 38993 ORA
Record Number: 199510726 / Last updated on: 1995-07-07
Original language: en
Available languages: en