Exploring the Dependence of Spectral Properties on Canopy Temperature with Ground-Based Sensors: Implications for Synergies Between Remote-Sensing VSWIR and TIR Data

作者：Christos H. Halios, Stefán Thor Smith, Brian J. Pickles, Li Shao, Hugh Mortimer · 发表于：Sensors · 年份：2025 · DOI：10.3390/s25030962 · 被引用次数：2 · 研究领域：Remote Sensing in Agriculture、Urban Heat Island Mitigation、Remote Sensing and Land Use

Spaceborne instruments have an irreplaceable role in detecting fundamental vegetation features that link physical properties to ecological theory, but their success depends on our understanding of the complex dynamics that control plant spectral properties—a scale-dependent challenge. We explored differences between the warmer and cooler areas of tree canopies with a ground-based experimental layout consisting of a spectrometer and a thermal camera mounted on a portable crane that enabled synergies between thermal and spectral reflectance measurements at the fine scale. Thermal images were used to characterise the thermal status of different parts of a dense circular cluster of containerised trees, and their spectral reflectance was measured. The sensitivity of the method was found to be unaffected by complex interactions. A statistically significant difference in both reflectance in the visible (VIS), near-infrared (NIR), and shortwave infrared (SWIR) bands and absorption features related to the chlorophyll, carotenoid, and water absorption bands was found between the warmer and cooler parts of the canopy. These differences were reflected in the Photochemical Reflectance Index with values decreasing as surface temperature increases and were related to higher carotenoid content and lower Leaf Area Index (LAI) values of the warmer canopy areas. With the increasingly improving resolution of data from airborne and spaceborne visible, near-infrared, and shortwave infrared (VSWIR)...