Characterizing Venus's clouds and hazes using CO2 absorption bands in
flux and polarization 1. Numerical simulations
Abstract
Retrievals of Venus cloud top altitudes have primarily been performed
using measurements of the total flux of sunlight that is reflected by
the planet across CO2 absorption bands. Linearly polarized fluxes are
known to be more sensitive to the properties of clouds and overlying
hazes than the total flux. Here, we present results of computations of
total and polarized fluxes of reflected sunlight in the wavelength
region between 1.4 and 1.5 μm, which covers a strong absorption band of
CO2. We perform an analysis of the sensitivity of the strength and shape
of the absorption band in polarization to the vertical distribution of
the cloud and hazes particles, i.e. cloud top altitude, and cloud and
haze scale heights, and illumination geometries. We show that the
reflected polarization signal at different locations and thus strengths
of the absorption band, can help to retrieve more information about the
scattering particles in the planetary atmosphere than the total flux
alone can. Spectropolarimetry from a Venus orbiter should provide
invaluable and independent information into the properties of Venus’s
clouds and hazes.