On the polarization angle of skylight reflected by natural surfaces: Properties and application for remote sensing of planetary atmospheres

In this study, we focus on the polarization angle of light scattered by terrestrial atmosphere-surface systems. The polarization angle describes the orientation of the plane in which the linearly polarized portion of light propagates. We show for skylight how this angle varies with the solar zenith angle and that, for skylight reflected by natural surfaces, these variations remain the same for wide ranges of atmospheric conditions and surface properties. This provides a tool for extracting scattering properties of the atmosphere from remote sensing observations of the Earth without any knowledge of the underlying surface. We demonstrate this principle for simulated data, and apply it to observations obtained by an airborne polarimeter over open oceans.