机载WIDAS数据的Landsat卫星反照率初步验证

Surface albedo is one of the key parameters in the investigation of surface energy balance. Accurate inversion of surface albedo is important for the evaluation on climate change. For the multi-angle reflectance data of an airborne Wide-angle Infrared Dual-mode line/area Array Scanner (WIDAS) in Genhe Region, Inner Mongolia, the Bidirectional Reflectance Distribution Function (BRDF) archetype-based algorithm was initially applied in forest experimental area. First, we extracted four BRDF archetypes based on the hotspot-corrected linear kernel-driven BRDF models, i.e., RossThickChen-LiSparseReciprocal and anisotropic flat index, in the experimental region of Genhe. Then, we applied these archetypes as a priori knowledge to the albedo inversion of WIDAS airborne data in the forest of the region. Finally, the albedo of WIDAS and the data observed by surface flux tower were used to verify Landsat albedo. In this study, we analyzed the robustness of the BRDF archetype-based algorithm in retrieving small-angle observations in forest experimental area. The results are as follows. (1) The surface albedo retrieved by the BRDF archetype-based algorithm has high accuracy and stability, and the total Root Mean Square Error (RMSE) of Landsat albedo was approximately 0.02 and deviation was 0.0057. (2) Given the available observation range of WIDAS in the experimental area of Genhe in 2016 was 25°, the BRDF archetype-based algorithm showed robust inversion capability in small observation angles. Therefore, when the multi-angle observation range was narrow, the albedo of airborne WIDAS retrieved by the BRDF archetype-based algorithm can be in good agreement with that of the Landsat, providing a means to effectively address the problem and validate the satellite albedo.