P- and L-band Retrieval of Root-zone Soil Moisture and Temperature Profiles as Quadratic Function

This paper discusses the promising application of P- and L-band passive measurements for the determination of root zone soil moisture and temperature profiles. In-situ soil moisture and temperature data were collected as a function of depth during the NASA GSFC PLEX19 experiment. Along with this soil data, a coherent model was employed to compute H- and V-pol brightness temperatures at frequencies of 0.8, 0.9, 1.1, and 1.4 GHz, with an observation angle of 35 degrees. These synthetic brightness data are then utilized to estimate soil moisture and temperature profiles at a depth of 60 cm, represented by quadratic functions. The inversion problem is formulated as a least squares problem and solved using the Adaptive Simulated Annealing method. We present four inversion examples with diverse values of soil moisture and temperature profiles. The selected results show that the root-mean-standard error between the retrieved and in-situ data is less than 0.052 cm³/cm³ for soil moisture, and 1.417 ℃ for soil temperature.