Interplay among gases, haze, and clouds in Titan’s atmosphere: From equatorial to polar conditions
- 1Laboratoire Enviromnements et Atmosphères Terrestres et Planétaires, Université de Reims Champagne Ardenne
- 2NASA Langley Research Center
- 3Univ. Grenoble Alpes, CNRS, IPAG
Abstract
Context. Cassini-Huygens observations have revealed Titan’s overall atmospheric composition. Although the main composition of cloud particles is generally established, other species might contribute to their formation, although their roles are poorly understood at present. This composition tends to vary with latitude and season due to global atmospheric circulation. Aims. We investigate the interplay among the aerosol-gas-cloud system under two equatorial and south pole post equinox conditions. Methods. We validated an updated 1D photochemical, microphysical, and radiative transfer model at the equator, where more constraints on hazes, clouds, and gas properties exist. We then analysed south pole post-equinox conditions, comparing gaseous species, haze, and cloud properties with equatorial conditions. A detailed chemical network was considered, along with an evaluation of the contribution of 23 gaseous species to cloud formation by condensation. The optical properties of clouds are calculated using a polyrefractive index derived from Bruggeman theory. The south pole enrichment of hazes and gases from global circulation was included and the outcomes were validated against Cassini/CIRS observations. Results. We present our results on the simultaneous condensation mass flux of gaseous species and the ensuing haze and cloud size distributions. In agreement with previous studies at the equator, HCN condenses below 80 km, followed by C2H6 below 50 km and CH4 below 30 km, with a significant contribution from C3H8 between 64 and 53 km. The modelled haze and cloud properties and gas abundances are consistent with Huygens/DISR and Cassini/CIRS constraints. South polar simulations show denser clouds forming at higher altitudes (≈250 km), initiated by HCN and C6H6 condensation, followed by HC3N, C3H8, C2H2, and C2H6, before methane dominates. Cloud size distributions remain similar to equatorial conditions, but with a higher density by two orders of magnitude We also explore C4N2 ice formation via secondary electrons from GCR interacting with cloud particles, without providing conclusive evidence for significant formation of C4N2 ice.
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BibTeX
@article{damiens2026interplay,
title = {{Interplay among gases, haze, and clouds in Titan’s atmosphere: From equatorial to polar conditions}},
author = {Damiens A. and Lavvas P. and Gronoff G. and Vuitton V.},
journal = {Astronomy \& Astrophysics},
year = {2026},
month = oct,
doi = {10.1051/0004-6361/202661189},
url = {https://doi.org/10.1051/0004-6361/202661189},
note = {CC BY},
}
RIS
TY - JOUR
TI - Interplay among gases, haze, and clouds in Titan’s atmosphere: From equatorial to polar conditions
AU - Damiens A.
AU - Lavvas P.
AU - Gronoff G.
AU - Vuitton V.
PY - 2026
DA - 2026/10/28
JO - Astronomy & Astrophysics
DO - 10.1051/0004-6361/202661189
UR - https://doi.org/10.1051/0004-6361/202661189
AB - Context. Cassini-Huygens observations have revealed Titan’s overall atmospheric composition. Although the main composition of cloud particles is generally established, other species might contribute to their formation, although their roles are poorly understood at present. This composition tends to vary with latitude and season due to global atmospheric circulation. Aims. We investigate the interplay among the aerosol-gas-cloud system under two equatorial and south pole post equinox conditions. Methods. We validated an updated 1D photochemical, microphysical, and radiative transfer model at the equator, where more constraints on hazes, clouds, and gas properties exist. We then analysed south pole post-equinox conditions, comparing gaseous species, haze, and cloud properties with equatorial conditions. A detailed chemical network was considered, along with an evaluation of the contribution of 23 gaseous species to cloud formation by condensation. The optical properties of clouds are calculated using a polyrefractive index derived from Bruggeman theory. The south pole enrichment of hazes and gases from global circulation was included and the outcomes were validated against Cassini/CIRS observations. Results. We present our results on the simultaneous condensation mass flux of gaseous species and the ensuing haze and cloud size distributions. In agreement with previous studies at the equator, HCN condenses below 80 km, followed by C2H6 below 50 km and CH4 below 30 km, with a significant contribution from C3H8 between 64 and 53 km. The modelled haze and cloud properties and gas abundances are consistent with Huygens/DISR and Cassini/CIRS constraints. South polar simulations show denser clouds forming at higher altitudes (≈250 km), initiated by HCN and C6H6 condensation, followed by HC3N, C3H8, C2H2, and C2H6, before methane dominates. Cloud size distributions remain similar to equatorial conditions, but with a higher density by two orders of magnitude We also explore C4N2 ice formation via secondary electrons from GCR interacting with cloud particles, without providing conclusive evidence for significant formation of C4N2 ice.
SN - 0004-6361
SN - 1432-0746
ER -