Effect of Forest Canopy Structure on Wintertime Land Surface Albedo: Evaluating CLM5 Simulations With In?Situ Measurements

Land Surface Albedo (LSA) of forested environments continues to be a source uncertainty in land surface modeling, especially across seasonally snow covered domains. Assessment and improvement global scale model performance has been hampered by the contrasting spatial scales resolution in-situ LSA measurements. In this study, point-scale simulations Community Model 5.0 (CLM5) were evaluated large range forest structures solar angles at two climatically different locations. measurements, using an uncrewed aerial vehicle with up down-looking shortwave radiation sensors, showed canopy structural shading exerted primary control on LSA. Diurnal patterns measured revealed strong effects both azimuth zenith angles, neither which adequately represented simulations. sparse environments, overestimated 66%. Further analysis lack correlation between Plant Area Index (PAI), descriptor CLM5, Instead, considerable fraction visible sensor's field view, increased further when only considering sunlit snow. The use effective PAI values as simple first-order correction for discrepancy simulated substantially improved results (64%–76% RMSE reduction). However, biases suggest need more generic solution, example, introducing metric that represents gap rather than assuming spatially homogeneous canopy.