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Two methods for retrieving sensible heat flux over a bare soil/wheat composite surface are compared within the framework of an experiment performed in June 1997 during the Alpilles/ReSeDA campaign in the South-East of France. The first one is based on field measurements using large aperture scintillometers. The principle of the method is first given and its application to composite surface discussed. The comparison against reference fluxes obtained from eddy correlation technique shows that scintillometryderived fluxes are overestimated by about 10%. A numerical experiment demonstrates this is induced by aggregation problems resulting both from non linearity in the relationship between structure parameter for refractive index C N 2 and sensible heat flux H, and from non uniform sensitivity of the scintillometer to C N 2 along the pathlength. The second method is based on the use of a simple surface energy balance model, SEBAL. The model is supplied with high spatial resolution remote sensing data from two airborne sensors in visible, near infrared and TIR bands. It provides maps of surface energy fluxes at a 20 m spatial sampling. A comparison against scintillometry derived fluxes (for June 9 th ) shows important discrepancies. They result from large errors in the estimation of the roughness length z 0 in the model. This demonstrates that the use of an empirical relationship based on NDVI only is inadequate for inferring this key parameter in SEBAL. 

Based on the principle of the simulation of the infrared thermal image, the static aircraft in the background of cement surface, at 2:00, 11:00, 14:00, are simulated under the remote sensors with spatial resolution of 5m and 10m. The evaluation is based on the radiance of target and the background extracted from the simulation image. The results indicate that the method in this paper can reflect the difference of radiance between the static target and the background which is useful in the target identification.

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