PROSAIL5B‐DR: A Radiative Transfer Model Extension for Dust Retention Effects on Vegetation Spectra

Abstract Dust deposition on urban vegetation alters canopy spectral reflectance and can reduce the reliability of parameter retrieval based on radiative transfer models (RTMs). However, conventional RTMs, including the coupled PROSPECT–SAIL (PROSAIL) model, do not explicitly represent these external optical effects. We developed PROSAIL5B‐DR by incorporating a dust‐induced absorption term into the leaf absorption coefficient, allowing dust effects to propagate to canopy reflectance. The dust mass‐specific absorption coefficient was calculated using the Mie theory. We evaluated model performance across dust retention levels, vegetation types, and urban environments. PROSAIL5B‐DR reproduced canopy spectral responses more accurately than PROSAIL5B while preserving the original model structure. It also reduced the simulation bias that increased with dust retention without adding redundant parameters. Explicitly representing retained particulate matter therefore improves canopy spectral simulations and provides a physically based approach for assessing vegetation optical properties in polluted urban environments.