Advancements in leaf-scale radiative transfer modeling: A review with focus on the PROSPECT model

Accurate estimation of leaf biochemical parameters is fundamental to understanding the physiological status of terrestrial vegetation at the leaf level. Leaf radiative transfer models (RTMs) provide an important theoretical basis for establishing the relationship between leaf spectral information and biochemical information, which simulates the radiative transfer processes and light interaction mechanisms within vegetation. As the most widely used leaf-scale RTM, the PROSPECT model can accurately simulate leaf spectral reflectance and transmittance by inputting leaf structural parameters and physical and chemical parameters. When combined with inversion technologies, RTMs can retrieve the biochemical parameters and leaf structure information of vegetation. It is of great significance to comprehensively review the application of RTMs in leaf spectral simulation and biochemical parameter inversion. The purpose of this paper is to review the development and applications of existing RTMs, focusing on the evolution of the PROSPECT model. The results show that the assumption of a uniform distribution inside the leaf is not completely realistic. Current understanding of leaf internal anatomy remains inadequate. In terms of inversion, physics-based RTMs are still underexplored. Furthermore, RTM inversion studies focused on dominant pigments such as chlorophyll, while carotenoids and anthocyanins received little attention due to their relatively low content.