Aerosols on the Giant Planets and Titan

Abstract

On the giant planets and Titan, like on the terrestrial planets, aerosols play an important part in the physico-chemistry of the upper atmosphere (P ≤ 0.5 bar). Above all, aerosols significantly affect radiative transfer processes, mainly through light scattering, thus influencing the atmospheric energy budget and dynamics. Because there is usually significant coupling between atmospheric circulation and haze production, aerosols may constitute useful tracers of atmospheric dynamics. More generally, since their production is directly linked to some kind of energy deposition, their study may also provide clues to external sources of energy as well as their variability. Finally, aerosols indirectly influence other processes such as cloud formation and disequilibrium chemistry, by acting either as condensation nuclei or as reaction sites for surface chemistry. Here, I present a review of observational and modeling results based on remote sensing data, and also some insights derived from laboratory simulations. Despite our knowledge of the effects of aerosols in outer planetary atmospheres, however, relatively little is understood about the pathways which produce them, either endogenously (as end-products of gas-phase photochemical or shock reactions) or exogenously (as residues of meteroid ablation).

Determination of the complex refractive indices of Titan haze analogs using photothermal deflection spectroscopy

“…This approach is especially useful in measuring the absorbance of films that simulate the action of UV or discharges on the atmospheres of planets or satellites (Courtin, 2005). The polymeric films formed by UV radiation or discharges have been reported to have little or no solubility in non-polar solvents like benzene or hexane (McKay, 1996;Coll et al, 1999) so should also be insoluble in Fluorinert or carbon tetrachloride, organics that are typically used in the PDS apparatus.…”

Characteristics of Titan's stratospheric aerosols and condensate clouds from Cassini CIRS far-infrared spectra

“…Tholin consists of a mixture of complex molecules, supposedly a representation of the composition of Titan's aerosol. Despite the many studies of tholin [see McKay et al (2001) and Courtin (2005) and references therein], only Khare et al (1984) have determined the optical constants of tholin at wavenumbers less than 200 cm −1 . The optical constants do not show any features below 200 cm −1 similar to Haze A.…”

Infrared spectroscopy and modeling of co-crystalline CO2·C2H2 aerosol particles. I. The formation and decomposition of co-crystalline CO2·C2H2 aerosol particles

“…[1][2][3][4][5][6] They can directly influence the radiative balance and thus the climate by absorbing and scattering the solar radiation. 2,7 They are involved in cloud formation either as a major cloud component or as cloud condensation nuclei. Furthermore, the large surface area of aerosol particles can provide reactive sites for various chemical processes.…”