Determination of continental surface emissivity and temperature from satellite observations.

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Surface emission depends on surface parameters, i.e. emissivity and temperature. Emissivity of land surfaces substantially varies with vegetation, soil moisture, composition, and roughness (Nerry et al. (1988); Salisbury and D'Aria (1992)). As emissivity depends on wavelength, it is referred to as spectral emissivity. Emissivity also depends on the viewing angle.

Continental surface emissivity in the thermal infrared window is a key parameter for estimating the surface radiation budget. The energy emitted from the surface is proportional to the spectrally integrated surface emissivity and depends on the surface temperature. A 10% error (from 0.9 to 1.0, for example) on the emissivity approximately corresponds to a 10% error in the energy emitted from the surface (a portion of which may be compensated by the reflected incoming radiation). Prabhakara and Dalu (1976); Ogawa et al. (2003).