A photochemical model of Titan's atmosphere and ionosphere

Krasnopolsky, V. A.

doi:10.1016/j.icarus.2008.12.038

Cited by 325 publications

(396 citation statements)

References 198 publications

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“…As noted in Krasnopolsky [2009], this functional form approximates the effects of upward propagating gravity waves. By adjusting the upper limit, K Max , the eddy diffusion coefficient will dictate the amount of mixing in the atmosphere and the altitude at which the atmosphere goes from a well-mixed state to a molecular diffusive state-the homopause.…”

Section: Examining Different Eddy Diffusion Formulationsmentioning

confidence: 88%

“…Figure 7 also shows the available constraints from the Huygens GCMS (light blue), the Cassini CIRS (yellow), and a range of mixing ratios from recent photochemical modeling studies in Krasnopolsky [2009] and Krasnopolsky [2010] (magenta). The data from GCMS and CIRS are obtained from much lower altitudes (near ∼100-200 km), while the mixing ratio from the photochemical modeling are appropriate for 500 km.…”

Section: The Impacts Of H 2 Chemistrymentioning

confidence: 99%

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Developing a self‐consistent description of Titan's upper atmosphere without hydrodynamic escape

et al. 2014

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In this study, we develop a best fit description of Titan's upper atmosphere between 500 km and 1500 km, using a one‐dimensional (1‐D) version of the three‐dimensional (3‐D) Titan Global Ionosphere‐Thermosphere Model. For this modeling, we use constraints from several lower atmospheric Cassini‐Huygens investigations and validate our simulation results against in situ Cassini Ion‐Neutral Mass Spectrometer (INMS) measurements of N2, CH4, H2, 40Ar, HCN, and the major stable isotopic ratios of 14N/15N in N2. We focus our investigation on aspects of Titan's upper atmosphere that determine the amount of atmospheric escape required to match the INMS measurements: the amount of turbulence, the inclusion of chemistry, and the effects of including a self‐consistent thermal balance. We systematically examine both hydrodynamic escape scenarios for methane and scenarios with significantly reduced atmospheric escape. Our results show that the optimum configuration of Titan's upper atmosphere is one with a methane homopause near 1000 km and atmospheric escape rates of 1.41–1.47 ×1011 CH4 m−2 s−1 and 1.08 ×1014 H2 m−2 s−1 (scaled relative to the surface). We also demonstrate that simulations consistent with hydrodynamic escape of methane systematically produce inferior fits to the multiple validation points presented here.

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Section: Examining Different Eddy Diffusion Formulationsmentioning

confidence: 88%

Section: The Impacts Of H 2 Chemistrymentioning

confidence: 99%

Developing a self‐consistent description of Titan's upper atmosphere without hydrodynamic escape

et al. 2014

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“…The CH radical is also suggested to be present in planetary atmospheres. 6,7 Its fast kinetics with saturated 56,57 and unsaturated hydrocarbons 14,58,59 indicates a barrierless entrance channel forming intermediates that may isomerize and dissociate to give the final products.…”

Section: Reactions Of the Ch Radical With Unsaturated Moleculesmentioning

confidence: 99%

Insights into gas-phase reaction mechanisms of small carbon radicals using isomer-resolved product detection

Trevitt

Goulay

2016

Phys. Chem. Chem. Phys.

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For reactive gas-phase environments, including combustion, extraterrestrials atmospheres and our Earth's atmosphere, the availability of quality chemical data is essential for predictive chemical models. These data include reaction rate coefficients and product branching fractions. This perspective overviews recent isomerresolved production detection experiments for reactions of two of the most reactive gas phase radicals, the CN and CH radicals, with a suite of small hydrocarbons. A particular focus is given to flow-tube experiments using synchrotron photoionization mass spectrometry. Coupled with computational studies and other experiment techniques, flow tube isomer-resolved product detection have provided significant mechanistic details of these radical + neutral reactions with some general patterns emerging. Disciplines Medicine and Health Sciences | Social and Behavioral Sciences ABSTRACTFor reactive gas-phase environments, including combustion, extraterrestrials atmospheres and our Earth's atmosphere, the availability of quality chemical data is essential for predictive chemical models. These data include reaction rate coefficients and product branching fractions. This perspective overviews recent isomer-resolved production detection experiments for reactions of two of the most reactive gas phase radicals, the CN and CH radicals, with a suite of small hydrocarbons. A particular focus is given to flowtube experiments using synchrotron photoionization mass spectrometry. Coupled with computational studies and other experiment techniques, flow tube isomer-resolved product detection have provided significant mechanistic details of these radical + neutral reactions with some general patterns emerging.

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“…4 The extreme reactivity arises from one singly occupied and one vacant non-bonding molecular orbital localized on the carbon atom. 5 Rate constants for the reaction of CH with numerous hydrocarbons ranging from methane (CH 4 ) 6,7 and acetylene (C 2 H 2 ) 7 to much larger Polycyclic Aromatic Hydrocarbons (PAHs) like anthracene (C 14 H 10 ) have been measured.…”

Section: Introductionmentioning

confidence: 99%

Direct detection of pyridine formation by the reaction of CH (CD) with pyrrole: a ring expansion reaction

Soorkia

Taatjes

Osborn

et al. 2010

Phys. Chem. Chem. Phys.

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A photochemical model of Titan's atmosphere and ionosphere

Cited by 325 publications

References 198 publications

Developing a self‐consistent description of Titan's upper atmosphere without hydrodynamic escape

Developing a self‐consistent description of Titan's upper atmosphere without hydrodynamic escape

Insights into gas-phase reaction mechanisms of small carbon radicals using isomer-resolved product detection

Direct detection of pyridine formation by the reaction of CH (CD) with pyrrole: a ring expansion reaction

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