THE EFFECT OF EMISSIVITY VARIATION ON SURFACE-TEMPERATURE DETERMINED BY INFRARED RADIOMETRY

During the international La Crau-experiment in 1987 the surface temper ature was measured using an infrared radiometer. Sensitivity of the de rived temperature to variations of surface emissivity and atmospheric radiation are investigated in this paper. A 1% error in emissivity wou ld bias the derived surface temperature about 0.5 K. The atmospheric r adiation was calculated using Lowtran-7 and radiosonde profiles. A 10% error in atmospheric radiation changes the derived surface temperatur e by about 0.1 K if the emissivity is 0.96. Comparison with atmospheri c radiation values derived from equations by Idso (1981) showed genera l agreement, but also a few very exceptional cases. Equations by Svend sen et al. (1990) yield values for surface temperature corrections tha t are about 5 times smaller than our values.