CHANGES IN SURFACE RADIATION CAUSED BY A SCATTERING LAYER AS CALCULATED USING RADIATIVE PERTURBATION-THEORY

The changes in surface flux (irradiance) and actinic flux (radiant ene rgy density) caused by an elevated scattering layer have been computed using radiative perturbation theory, a technique which is well suited to addressing such questions. A range of layer elevations and solar z enith angles was considered, for wavelengths of 300 nm and 550 nm. Our results for 300 nm are in broad agreement with a recently published s ingle-scattering calculation, showing large enhancements when both lay er elevation and solar zenith angle are high. Our results for 550 nm s how a somewhat unexpected enhancement in actinic flux for small solar zenith angles.