Retrieval of Venus' clouds and hazes properties with polarimetric data from SPICAV/VEx

Abstract : The study of Venus’ cloud layers is important in or- der to understand the structure, radiative balance and dynamics of the Venusian atmosphere. Polarization measurements have given important constraints for the determination of the constituents of the clouds and haze.From ground based observations, Hansen and Hovenier[3], using a radiative transfer model includ- ing polarization, found that the main cloud layers be- tween 50 and 70 km consist of r ∼ 1 μm radius spher- ical droplets of a H SO -H O solution. In the early 1980s, Kawabata[4] used the polarization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the overlying haze. They found that the haze layer is composed of smaller parti- cles with r ∼ 0.25 μm and similar refractive indices. Our work reproduces the method used by Hansen and Kawabata[3, 4]. We applied a radiative transfer model with polarization on the polarization data of the SPICAV-IR instrument on-board ESA’s Venus Ex- press. Our aim is to better constrain haze and cloud particles at the top of Venus’s clouds, as well as their spatial and temporal variability.