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A two-layer model used to get the estimated values of crop transpiration by inversion using remote sensing data, which has been proved effective at some agricultural-ecological sta-tions, is first discussed. An important part of it is the temperature separation model (in which thesurface temperature in a mixed pixel is separated into soil surface temperature and crop canopysurface temperature) on the basis of bi-temporal radiometric temperature in a mixed pixel and its thermal inertia. To improve the inversion, the authors put forward some new algorithms, including an algorithm for the estimation of regional emissivities, a static feedback algorithm using surfacetemperature for the extension of air temperature at ecological stations to the region surroundingthem and a spatial extension algorithm for calculating the wind speed 2 m above the ground withsurface roughness and radiometric temperature. Finally, regional distributions of crop transpiration (CT) and soil water use efficiency (SWUE) in North China were calculated pixel by pixel usingNOAA-AVHRR data and surface measurements and calibrations. The results provide a way toassess the effects of various agricultural practices on SWUE by using remote sensing data inNorth China in spring.
A two-layer model used to get the estimated values of crop transpiration by inversion using remote sensing data, which has been proven effective at some agricultural-ecological sta- tions, is first discussed. An important part of it is the temperature separation model in which thesurface temperature in a mixed pixel is separated into soil surface temperature and crop canopysurface temperature) on the basis of bi-temporal radiometric temperature in a mixed pixel and its thermal inertia. To improve the inversion, the authors put forward some new algorithms, including an algorithm for the estimation of regional emissivities, a static feedback algorithm using surface temperature for the extension of air temperature at ecological stations to the region surrounding them and a spatial extension algorithm for calculating the wind speed 2 m above the ground with surface roughness and radiometric temperature. Finally, regional distributions of crop transpiration (CT) and soil water use efficiency ( SWUE) in North China were calculated pixel by pixel usingNOAA-AVHRR data and surface measurements and calibrations. The results provide a way toassess the effects of various agricultural practices on SWUE by using remote sensing data in North China in spring.