An experimental analysis of thermal response numbers as indicators of vegetation water-stress for remote sensing

Imanishi, J., Sugimoto, K. and Morimoto, Y. 2003. An experimental analysis of thermal response numbers as indicators of vegetation water-stress for remote sensing. Journal of the Japanese Society of Revegetation Technology 29(1), 159-164. (2003.9) (in Japanese)

Abstract

The thermal response number (TRN) is the thermal inertial indicator that represents the degree of surface temperature change in response to input radiative energy. In this research, we conducted a canopy-level experiment using seedlings in order to demonstrate the possibility to detect vegetation water stress using TRN and the alternative thermal response number (ATRN), which we suggested as the alternative indicator that reduces the two observations of TRN into one using the air temperature about 30 min later from dawn. As a result, the TRN(dawn), which is calculated from the observed surface temperatures at around dawn and a time between 9:00 and 11:30 using airborne TABI equivalent thermal infrared sensor (relative precision of 0.1 ℃) and the measured downward short- and long-wave radiation at ground, was potentially capable of detecting the existence of water stress of the vegetation about 4 in LAI.