Effect of soil moisture on microwave scattering for remote sensing

The main objective of remote sensing is to design space borne microwave sen sors to sense a target and derive useful geophysical parameters. For this p urpose, the knowledge of the target characteristics must be obtained throug h ground based remote sensing. In this paper, soil has been taken as the ta rget. Various percentages of gravimetric soil moisture (m(g)) have been tak en for establishing its relation with the scattering coefficient (sigma(0)) for both like polarizations at X-band frequencies. A linear model has been developed for correlating these two variables (i.e. m(g) and sigma(0)). Us ing this model, regression analysis has been done for obtaining different r egression parameters and predicted values. Treating measurements from bare smooth soil fields with different soil moistures, the data were analysed to examine the effect of soil moisture on scattering coefficient (sigma(0)) a t 9.50GHz frequency in X-band. The scattering coefficient increases with in crease in soil moisture content. Different regression parameters have been obtained, which show that the best look-angle is at 25 degrees for HH-pol a nd 60 degrees for VV-pol for observing sigma(0) from bare moist soil. Data analysis indicated that the basic cause and effect relationship between the sensor measurements and soil moisture can be extrapolated from theory and small-scale tests to larger resolution elements observed by the sensing air craft. These results indirectly provide reference data for a satellite-born e remote sensor. From the results, the look angles suitable for operation w ith radar antennas can be suggested.