Significance of Vegetation in Interpreting Thermal Radiation from a Terrestrial Surface

Abstract

The regions between crop rows are modeled as infinitely long diffuse cavities. Geometrical view factors are calculated, accounting for reflected radiation emanating internal to the cavity and from the background sky. A ?cavity? emissivity dependent on local geometry is defined to allow for correcting apparent temperatures to true temperatures. The total emissivity appropriate for correcting aircraft thermal data is then calculated by averaging all emissivity components to account for soil, crop and background. It is shown that even for the lowest crop and vegetation emissivities if the crop height-to-spacing ratio is greater than 1, the composite emissivity is greatly increased giving rise to a decreased error in remotely sensed temperature data.