An Improved Canopy Brightness Temperature Model Based On Spectral Invariants

As one of the most important spectral invariants, the recollision probability (p) is a crucial physical parameter that describes the interaction process between the photon and the canopy. This study discusses the applicability of the recollision probability in the thermal infrared (TIR) domain by Monte Carlo simulation. By extending the recollision probability from the VNIR to the TIR, an Improved Canopy Brightness Temperature model based on the p theory (ICBT-P) is introduced to simulate the canopy thermal radiation directionality. A cross-validation between the analytical ICBT-P model and 3D DART model was conducted, yielding R
²
values over 0.99 in two homogeneous scenarios where the leaf and soil components exhibit a significant temperature difference. In other two homogeneous scenarios where the leaf and soil components have the same temperature, the R
²
values are over 0.98. The average brightness temperature difference across the four typical scenes is 0.08K. This new model (i.e., ICBT-P) has the potential to be used for the canopy temperature estimation and the component temperature separation of leaves and soil.