APPLICATION OF ASYMPTOTIC EXPRESSIONS FOR COMPUTING THE POLARIZED RADIATION IN OPTICALLY THICK PLANETARY-ATMOSPHERES

For optically thick plane-parallel homogeneous atmospheres the interna l and emerging radiation may be calculated using one of the standard m ethods to solve radiative transfer problems. Alternatively, this radia tion may be approximated by using so-called asymptotic expressions, wh ich involve the reflection properties of the corresponding semi-infini te atmosphere and the leading eigensolution of the equation of radiati ve transfer. In this paper we illustrate the accuracy of these approxi mations for an atmosphere containing Venus cloud particles. It is show n that for conservative and near conservative scattering in this Venus atmosphere the approximations give accurate results for the reflected , midlevel and transmitted polarized radiation if the optical thicknes s is larger than 3,20 and 10, respectively. In addition, accurate nume rical values of quantities pertaining to the asymptotic expressions ha ve been tabulated.