Study On The Vegetation Canopy Water Based On Hyperspectral And Multiangular Remote Sensing Information

The main purpose of this paper is to detect effectively winter wheat canopy water under low vegetation coverage in the North China based on multi-sensors satellite remote sensing information, hyperspectral and multianglar field experiment.First, we observed winter wheat canopy multiangular spectrum and crop physiological parameters at different vegetation coverage and water condition. Some parameters are selected to run the PROSAIL model for the sensitive analysis, and compared field data with the simulating data. Then we built and computed a series of vegetation water indexes for eliminating effects of soil background, compared correlation coefficients of all indexes with FMC (Fuel Moisture Content) and EWT (Equivalent Water Thickness), separately. The satatistical relationships between the water content indexes with MODIS, MISR spectrums simulated by PROSAIL model and FMC was set up. Third, the spatical patterns of winter wheat canopy water content in North China were given by using the MODIS and MISR image data in the North China on April 13th, 2007.The main conclusions in this study are as follows:(1) Soil and crop water conditions obviously influenced on the LAI, FMC and EWT. However, unobviously on chlorophyll Cab in each crop development stage.(2) In principal plane, the backward reflectance was larger than the forward reflectance. It is because that occupation percent of field viewing of sensor was greatly changed in different directions. Canopy reflectance changed with the observing zenith angle.(3) It is a good consistency between field spectrum data and simulative data in turning green and elongating stage of winter wheat. The PROSAIL model could be suit for simulating vegetation spectrum at the middle angle of forward and small angle of backward in principal plane on the condition of low coverage.(4) Results show that 60°and -30°observing zenith angle are more proper angles for our study. There are some indexes with combination of 760nm and 2130nm and combination of 760nm and 970nm on 60°observing zenith angle, and other indexes with combination of 760nm and 1640nm and combination of 760nm and 855nm on -30°observing zenith angle could be used to indicate FMC.