Air-canopy temperature difference for fluorescence emission models

Precise canopy temperature (CT) determination of a boreal forest region was needed within SIFLEX-2002 to improve the understanding of fluorescence processes. Taking into account sky radiance effects and emissivity correction, CT was measured with an accuracy of /spl plusmn/0.4 K using the CE 312 radiometer. An inverse correlation between Photochemical Reflectance Index (PRI) and CT, solar illumination and sensible heat flux has been detected in the comparative analysis of these physical quantities.