Separation of temperature and emittance in remotely sensed radiance measurements

The remote determination of surface temperature and surface spectral emittance by use of airborne or satellite-borne thermal infrared instruments is not straightforward. The radiance measured is a function of surface temperature, the unknown surface spectral emittance, and absorption and emission in the intervening atmosphere. With a single measurement, the solution for temperature and spectral emittance is underdetermined. This article reviews two of the early approximate methods which have been fairly widely used to approach this problem.