A Study Of Seasonal Variation And Models Of Directional Thermal Radiance Over Row-planted Winter Wheat Canopy

The thermal emission directionality of complicated land surface is one of the most important basic research topics of TIR remote sensing, which has been investigated from the end of 1970s. Based on the foregone researches, this dissertation studied the thermal emission directionality of row-planted winter wheat canopy. Three parts of work have been done, (a) Field measurement of directional thermal radiance over wheat canopy, (b) Assessment of the applicability of existed models for four typical growth stages, (c) Building new TIR directional model to explain the directional thermal radiation.We measured the directional thermal radiance of wheat canopy for a whole life circle. A goniometer system and a thermal camera were employed. And we have brought out a scheme for data processing. It was found out that the sunlit side and shaded side of one ear has different brightness temperature. The differences may be op to is 3 degree generally, that significantly affect the directional thermal radiance of the canopy.The whole life circle of wheat can be divided into four typical stages according the canopy geometric structure and thermal radiance character. The first stage is when plants are scattered and bare soil isolates each plant. The second one is when the neighboring plants along row direction overlapped each other, and rows of vegetation and rows of bare soil are interlaced. The third stage is when neighboring plants each other either along row or crossing row. The fourth stage is when ears appear. We analyzed existed models and found each model is suitable to a specific stage.To build a new model to be suitable to the whole growth stage, we take single...