Investigating the condensation of benzene (C6H6) in Titan's South Pole
Abstract
Following the northern spring equinox in 2009, Titan's global atmospheric circulation reversed within 2 years. This event also increased the mixing ratios of benzene (C6H6) and other species at the South pole. Simultaneously, a strong cooling (<120 K) favored the condensation of organic molecules at unusually high altitudes (>250 km). C6H6 ice has been detected by the Cassini Composite Infrared Spectrometer (CIRS) in the South polar cloud system[1], but the existing laboratory data is insufficient to allow models to reproduce the formation of the observed cloud system.
Here, we present the overall scope and first experimental results of a new project that combines Earth Sciences and Planetary Sciences expertise and synergistic experimental[2,3], modeling[4] and observational work[1] to investigate the chemical and microphysical processes leading to the formation of this cloud system. The project goals are: 1) (laboratory) to measure the vapor pressure of C6H6 at Titan-relevant temperatures (140-175 K) using the NASA Ames Atmospheric Chemistry Laboratory[2], 2) (laboratory) to produce analogs of Titan's aerosols using the Titan Haze Simulation experiment developed on the Ames COSmIC facility[3] and investigate the conditions required for condensation of C6H6 on them, 3) (observations) to analyze CIRS data[1] and derive temperature profiles and C6H6 mixing ratios, 4) (model) to use our experimental and observational data to constrain nucleation and condensation in the microphysical models[4] and determine expected cloud altitudes and particle sizes, and 5) (observations) to compare our experimental data and modeling output with observations from CIRS in the 9-17 µm spectral region[1], in order to better understand the molecular composition of this cloud system. References: [1] Vinatier, S. et al., Icarus 310, 89-104, 2018. [2] Iraci, L. T. et al., Icarus 210 (2), 985-991, 2010. [3] Sciamma-O'Brien, E. et al., Icarus 289, 214- 226, 2017. [4] Barth E. L., Planet. Space Sci. 127, 20-31, 2017.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.P11D3477D
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0320 Cloud physics and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 5405 Atmospheres;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5422 Ices;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS