Fig. 1. Sampling site distributions of target regions. (a) Target region A; (b) target region B

Fig. 2. Relationship between imaginary part of soil dielectric constant and soil salinity

Fig. 3. Relationship between soil dielectric constant and soil volumetric water content. (a) Real part of dielectric constant; (b) imaginary part of dielectric constant

Fig. 4. Relationship between measured data and simulated dielectric constant. (a) Simulated dielectric constant-measured dielectric constant; (b) volumetric water content-simulated dielectric constant; (c) soil salinity-simulated dielectric constant

Fig. 5. Relationship between soil dielectric constant and backscattering coefficient. (a) Real part of dielectric constant; (b) imaginary part of dielectric constant

Fig. 6. Backscattering coefficient images at four kinds of polarization modes. (a) HH polarization; (b) VV polarization; (c) HV polarization; (d) VH polarization

Fig. 7. Relationship between radar image backscattering coefficient and AIEM simulated backscattering coefficient at four kinds of polarization modes. (a) HH polarization; (b) VV polarization; (c) VH polarization; (d) HV polarization

Fig. 8. Grayscale map of soil salinity index

Fig. 9. Correlation analysis between measured soil salinity and soil salinity index