Radiative transfer calculations with scattering and absorption by aerosols and molecules are used to estimate the magnitude of the Ring effect in the O2A band. Rotational Raman scattering significantly alters the A band line depths and shapes for a satellite nadir-viewing case at high solar zenith angles in the absence of thick clouds. In the limb view, at low spectral resolution, the only impact of rotational Raman scattering is that it significantly reduces the radiance in the shoulder of the R branch. The latter effect is also observed for zenith viewing geometry from the ground. ¿ 2000 American Geophysical Union