Development of semi-physical model for microwave and optical wavelengths

Abstract

This work presents a method of physical integration of active passive microwave interaction models to forward model the backscattering coefficient (BSC) for L-band, brightness temperature (TB) for L- and C-Band. To model these regions a model named SPIN (Spectrum Invariant Interaction) model is introduced. The model is obtained by combining vector and scalar radiative transfer (VRT, SRT) equations, respectively. The equations of SPIN model are flexible with respect to selected coordinate systems and are solved kernel based, which ensures a highly invertible behavior for futures inversion attempts. The application of the model is shown using the measurements during the growing cycle of corn from the Eleventh Microwave, Water, and Energy Balance Experiment (MicroWEX-11). The forward modelled BSC values for L-band correlate strongly with the vertical and horizontal polarization measurements with a uRMSD (unbiased Root Mean Square Distance) of 0.40 [dB] and 0.37 [dB], respectively. In addition, the modeled brightness temperature for both polarization states at C-band are also highly correlated with the MicroWEX-11 measurements (uRMSD: 1.55 [K]) and are less correlated with L-band (uRMSD for vertical polarization: 1.19 [K] and uRMSD for horizontal polarization: 4.67 [K]). Experimentally, the SPIN model is also applied to the optical region. For the optical region the results are compared with the PROSAIL model. The optical results are consistent with the results of other optical models (Pearson 0.99, R2 0.98) like PROSAIL.