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The Earth Radiation Budget Experiment carries a three‐channel scanning radiometer and a set of nadir‐looking wide and medium field‐of‐view instruments for measuring the radiation emitted from earth and the solar radiation reflected from earth. This paper describes the algorithms which are used to compute the radiant exitances at a reference level (“top of the atmosphere”) from these measurements. Methods used to analyze data from previous radiation budget experiments are reviewed, and the rationale for the present algorithms is developed. The scanner data are converted to radiances by use of spectral factors, which account for imperfect spectral response of the optics. These radiances are converted to radiant exitances at the reference level by use of directional models, which account for anisotropy of the radiation as it leaves the earth. The spectral factors and directional models are selected on the basis of the scene, which is identified on the basis of the location and the long‐wave and shortwave radiances. These individual results are averaged over 2.5° × 2.5° regions. Data from the wide and medium field‐of‐view instruments are analyzed by use of the traditional shape factor method and also by use of a numerical filter, which permits resolution enhancement along the orbit track.
Smith et al. (Thu,) studied this question.