Characterizing the effects of atmospheric and land surface factors on the diurnal variation of land surface albedo (DVLSA) over vegetated surfaces.

• The effect factors of diurnal variation of albedo were investigated quantitatively. • The diurnal variation of albedo is crucial for solar energy research. • The solar zenith angle and leaf angle distribution are the most sensitive factors. The diurnal variation of land surface albedo (DVLSA) is crucial for research on solar energy. It is necessary to systematically and quantitatively investigate the effects of atmospheric and land surface factors on the DVLSA. This paper explores the influencing factors of DVLSA over vegetated surfaces based on field observations, laboratory experiments, and simulated data. DVLSA over vegetated surfaces is influenced by four main types of factors: solar illumination geometries, canopy structure, canopy components, and atmospheric conditions. Through global sensitivity analysis, the study identifies sensitive parameters to DVLSA over vegetated surfaces, including solar zenith angle (SZA), leaf angle distribution (LAD), leaf area index (LAI), soil dryness index (SDI), leaf dry matter content (LDMC), and aerosol optical depth (AOD). Their respective contributions are approximately 30%, 24%, 17%, 10%, 4%, and 7%, respectively. Further analysis reveals that when SZA is less than 50°, the DVLSA is minimally influenced by these factors. However, when SZA exceeds 50°, the sensitivity of DVLSA to these factors increases with rising SZA. The DVLSA over vegetated surfaces is significantly influenced by canopy structure, exhibiting a nonlinear increase with growing LAI and LAD. Among various land cover types, the DVLSA of forests is the strongest, followed by that of cropland and grassland, while that of soil is the weakest. Under a sparse canopy, the DVLSA increases linearly with higher SMC and LDMC. Additionally, it increases with reduced leaf surface roughness and increased soil surface roughness. Under clear sky conditions, the DVLSA decreases linearly as the AOD increases. [ABSTRACT FROM AUTHOR]