DETECTING SOIL MOISTURE UNDER CANOPY BY MEANS OF NOAA AVHRR

摘要

Handan Municipal Region in Hebei province of China was chosen as study area. Both insitu observed data (i.e. soil moisture S_(m') canopy temperature T_(c') air temperature T_(a) and soil surface temperature T_(s)) and NOAA AVHRR data were collected simultaneously from 11 sample stations within this area during one year period (1990). All of the NOAA AVHRR different channel data and insitu measured data were used in correlation and regression analysis. Theoretical temperature differential method using NOAA AVHRR thermal band data T_(nc) as the canopy temperature, insitu measured air temperature and soil moisture was applied in comparing correlation and regression models among them at the beginning stage. NOAA AVHRR data and insitu collected soil moisture data were also used in determining the correlation coefficients and regression model with the modification of vegetation index data which were obtained by using of NOAA AVHRR channel one and channel two data at the final stage. The results show that using brightness temperature obtained from AVHRR channel 3, channel 4 and Soil moisture have a very significant correlation with the modification of the vegetation index in day time. This correlation is more significant than the former method (using T_(nc), T_(a) and S_(m)) with correlation coefficient of -0.88. The reason of the deviation of these two method is also analyzed in this paper. This method for monitoring soil water contents is the most feasible way which has not been found both in China and other countries. It has a significant use in agriculture activity.