Spherical Albedo Research Articles

Multiple scattering in planetary atmospheres

Numerical results of reflection and transmission on plane-parallel layers with strongly anisotropic scattering are reviewed. A convenient method is to use successive scattering, doubling, and asymptotic fitting, in three size ranges. The eigenvalues determining the convergence of series in the doubling method are shown and eigenvalue problems in the other steps are described. The distribution of incident energy over reflection, transmission and absorption is shown for a wide range of parameters. Accurate tests made with different phase functions with the same anisotropy parameter g show that the moments of the reflection function (plane albedo, spherical albedo) hardly change at all but that differences up to 20 per cent, mainly due to single scattering, persist in the reflection function itself. The azimuth-dependent terms are shown to converge rapidly with growing Fourier order m and with growing order of scattering n, thus permitting various shortcuts in the computation.

The effect of coarse angular discretization on calculations of the radiation emerging from a model cloudy atmosphere

The problem of multiple scattering by a plane parallel atmosphere with anisotropic phase functions typical of terrestrial cloud particles is considered. The albedos and angular distributions of the emergent radiation are computed for a variety of cloud models. The number of angular directions used in the computations are varied to assess their effect upon the computed radiances. The results demonstrate that it requires an extremely fine angular mesh to compute accurately the angular distribution of the emergent radiation for possible comparison with observed cloud radiances when errors ≲1 per cent may be tolerated. On the other hand, the computations of the integrated effects of spherical and local albedos differ by ≈2 per cent in overall cloud thicknesses when computed with eight and thirty-two angular directions. This results indicates the possible reduction in computational expenditure if only the integrated effects are required.

Monochromatic Phase Curves and Albedos for Venus

Abstract Photoelectric observations of Venus were made between 1963 and 1965 from the Harvard College Observatory's Boyden Station in South Africa. Interference filters with half widths between 50 and 200 A were used to isolate ten narrow bands between 3150 A and 1.06 μ; observations were also made in the standard UBV bands. Phase curves are presented and compared with previous observations. The spectral reflectivity is found to be strongly dependent on both wavelength and phase angle. Spherical (Bond) albedos are determined as a function of wavelength. The radiometric albedo of Venus is estimated to be A*=0.77±0.07, where the principal source of uncertainty is the visual magnitude of the sun.