Researches On Dielectric Behavior Of AIEM Model And Its Response To The Radar Backscattering Coefficients

Soil salinization is the salt content of the soil profile or groundwater with the capillary water rise to the surface, evaporation process of salt accumulated in the earth’s surface. The influence of human activities and natural conditions to the water and salt together lead to land degradation, soil salinization is one of the main forms of its constitute. Soil salinization is common in huge evaporation, high underground water level, has became the important factor of the development of oasis agriculture. In our country especially in Xinjiang, the problem of soil salinization is serious, restrict the development of oasis economy, therefore, learn from the occurrence and development mechanism of the soil salinization cause of salinization and development trend, can fundamentally solve the problem of soil salinization, thereby giving impetus to the development of oasis economy. Microwave remote sensing can be all-weather, all-day detection feature of target, and can penetrate the soil, vegetation and snow, at the same time it can not affected by atmosphere, and also not be restricted by the light conditions, obtain soil information directly, make up for the deficiency of the optical remote sensing in monitoring soil salinization, those advantages of microwave remote sensing in monitoring soil salinization provides theoretical and experimental basis.Dielectric constant is an important factor in soil characteristics, using dielectric constant monitoring of saline soil water and salt content, and use the remote sensing method to get soil salt and water is uncommon. Based on this, firstly, choose the optimal model of dielectric, analysis the response of the dielectric constant and dielectric various parameters in the model, use field measured dielectric constant verify the applicability of this model. Secondly, in the certain cases of Angle of incidence and the roughness, the simulation of dielectric constant to the measured soil salt content, water content input to the AIEM model, simulate the backscatter coefficient of surface, at the same time deal with four polarization mode of microwave remote sensing image, extract the backscatter coefficient of feature points, analysis its fitting relationship, for the soil salinization in arid areas which provides the theoretical foundation of microwave remote sensing inversion.The results show that:(1) through the response of the dielectric constant and dielectric model parameters analysis, get the relationship between dielectric constant and the volumetric water content, salt content and soil bulk density: soil volumetric water content and soil permittivity real part significant response, fitting degree of 99%; Dielectric constant imaginary part mainly depends on the salt content, the influence degree of the volumetric water content for the imaginary part is less than the strength of the salt effect. In addition, the dielectric constant of field measured soil salt and water content of simulation and the analysis of the field soil dielectric constant fitting, the fitting effect is good, explain the Dobson dielectric model is suitable for oasis.(2)Based on the AIEM model, establishes the model database of soil salinity and water volume, analysis the response between water and salt and backward scattering coefficient. In the condition of certain salt, incident angle and the surface roughness, backward scattering coefficient increases with the increase of water content, significant response. By further analyzing the soil salinity response to the scattering coefficient, the curve characteristics is similar, soil salinity has less influence to the backward scattering coefficient; in the condition of certain water content, incident angle and the surface roughness, with the increase of salinity the backward scattering coefficient increases slightly, but the overall curve tending to straight line, change is not obvious, the response is smaller.(3) Using AIEM model, under the condition of a certain incident Angle, roughness, simulate the backscatter coefficient of sample point, and process the radar image, extract backward scattering coefficient of the corresponding points, analysis of AIEM model and radar images’ backward scattering coefficient, found that no significant correlation between VV with HH polarization mode, HV and VH cross polarization radar imaging and model shows significant correlation, the correlation coefficient R2 is 0.65. Dielectric constant as the most important parameters in AIEM model, dielectric constant is the main factors influencing the radar image backward scattering coefficient, so using dielectric constant to monitoring soil salinity and water content has a certain potential. In addition, provides a new way of thinking, using of microwave remote sensing image retrieval soil water content.