Model validation of the polar clouds at Saturn as inferred by Cassini/VIMS data in the visual range

ABSTRACT In this preliminary study the goal of the work is to extend the analysis of a set of clouds observed in the South Polar atmosphere of Saturn by VIMS on Cassini, from the infrared range (previously done) to the visual range. As a starting point we considered the best fit values (least square method) of the parameters for the same set of clouds, calculated through a line-by-line radiative transfer model applied to the spectral information from the infrared channel of VIMS in the range 1-5 µm. Those same parameters like composition, particle concentrations and sizes have been used with a different radiative transfer code suitable for working in the range of wavelengths 0.3-1.0 µm (LibRadtran). As our first simulations do not well agree with the observed spectra, an improvement is suggested to reduce the relative difference between the model and the measurement. Possible sources of the observed discrepancies and the procedure to reduce them, are discussed.