Nocturnal clear-sky directional downwelling infrared temperture measurements in a forest canopy

摘要

Presented is a ground-based measurement technique for quantifying the directional properties of the infrared radiation regime within a forest canopy with regard to mapping the canopy transmission over the upwards facing hemisphere. Implications are discussed for remotely sensed canopy temperature measurements and models of canopy transmission. The technique involves taking narrowband measurement scans throughout the hemisphere using a narrow view angle, narrow spectral band radiometer that measures predominantly within the water vapour transmission window. Measurements made under both clear skies and within a dry sclerophyll Eucaltpus canopy are presented and discussed.