In remote sensing, the kernel-driven model (KDM) is widely used for reflectance modeling due to its simple mathematical formulation and computational efficiency. However, in contrast to non-desert scenes, desert shrub canopies are characterized by woody components that are significantly larger than the leaf areas. This deviates the assumptions of Beer's law, which is based on translucent leaves. Moreover, desert environments present a special “background” composed of sand, gravel, saline land, and biological crust, further complicating reflectance modeling. These complexities pose significant challenges for the application of KDM in desert regions. To address these issues, this study introduces a volume-scattering kernel derived from the analytical Gutschick-Wiegel (G-W) solution with a single-angle configuration, aiming to better represent radiative transfer in sparse desert canopies. The model also incorporates different geometric-optical kernels designed to account for the structure of sparse shrubs and the heterogeneous biological crust in desert, using a cover parameter to adjust their respective weights. Furthermore, terrain factors and hotspot functions were integrated to account for coherent backscattering and anisotropic scattering effects. Based on these considerations, this study proposes a new KDM, i.e., the Hotspot Li-Sparse Roujean Terrain (HLSRT) model. The HLSRT model was extensively validated using field measurements and satellite observations. It achieved a low average in situ bias for the red and near-infrared band (NIR) bands (bias = 0.005) and a low root mean square error (RMSE = 0.0299) against satellite data. Compared to existing KDMs, the HLSRT model demonstrated superior performance in reflectance modeling. These results indicate that the HLSRT model offers a reliable semi-empirical tool for modeling radiative transfer and supporting inversion studies in complex desert environments.
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