Study on the relationship between soil moisture and its dielectric constant obtained by space-borne microwave radiometers and scatterometers

For obtaining spatial-temporal soil moisture information in large range, a study on the relationship of soil moisture and dielectric constant obtained by space-borne microwave radiometers and scatterometers data was performed. Microwave signal is much related to dielectric constant of object observed, and soil dielectric constant is decided by soil moisture, this is the basis of using microwave remote sensing technology for soil moisture monitoring. This study focuses on the transformation of soil moisture and soil dielectric constant. The Dobson semi-empirical model was used to build a simulated database, then, the coefficients calibrated of Hallikainen formula by the least square regression method at radiometer SMOS(1.4GHz), AMSR-E(6.9GHz), and scatterometer ERS-WCS and METOP-ASCAT (both at 5.3GHz) frequency-points were performed to set up the simplified models to related the real part of the dielectric constant and the soil volumetric moisture content. The validations are performed using both simulated data of the Dobson model and in-situ observations, the results show that the simplified models have good accuracy and practicality.