A coupled dynamics-microphysics model of Titan's atmosphere

Rannou, P.; Hourdin, F.; McKay, Christopher P.; Luz, D.

doi:10.1016/j.icarus.2004.03.007

Cited by 117 publications

(135 citation statements)

References 45 publications

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“…This suggests that at the probed altitudes and over the regions and time observed, the wind speed is not significantly lower than jet streams (180-250 m/s) at high latitudes deduced by others [Hubbard et al, 1993;Rannou et al, 2004;Bouchez, 2004]. Based on our measurements, such deduced jets would approach supersonic speeds at the high latitudes.…”

Section: Discussionsupporting

confidence: 65%

Titan's stratospheric zonal wind, temperature, and ethane abundance a year prior to Huygens insertion

Kostiuk

Livengood

Hewagama

et al. 2005

Geophysical Research Letters

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Section: Discussionsupporting

confidence: 65%

Titan's stratospheric zonal wind, temperature, and ethane abundance a year prior to Huygens insertion

Kostiuk

Livengood

Hewagama

et al. 2005

Geophysical Research Letters

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“…On Mars, assuming the right amount of dust in the atmosphere it has been relatively easy to simulate the thermal structure of the atmosphere and the behaviour of atmospheric waves, such as thermal tides and baroclinic waves [70][71][72][73][74][75][76], to reproduce the main seasonal characteristics of the water cycle [77,78] or to predict the detailed behaviour of ozone [79,80]. On Titan, GCMs have anticipated the super-rotating wind fields with amplitude and characteristics comparable to observations [81,82] and allowed to simulate and interpret the detached haze layers [83,84], the abundance and vertical profiles of most chemical compounds in the stratosphere and their enrichment in the winter polar region [85], the distribution of clouds [86] or the detailed thermal structure observed by Huygens in the lowest 5 km [87]. On Venus, the development of 'full' GCMs (i.e.…”

Section: (B) Modelling Terrestrial Planetary Climate (I) From One-to mentioning

confidence: 99%

Possible climates on terrestrial exoplanets

Forget

Leconte

2014

Phil. Trans. R. Soc. A.

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What kind of environment may exist on terrestrial planets around other stars? In spite of the lack of direct observations, it may not be premature to speculate on exoplanetary climates, for instance to optimize future telescopic observations, or to assess the probability of habitable worlds. To first order, climate primarily depends on 1) The atmospheric composition and the volatile inventory; 2) The incident stellar flux; 3) The tidal evolution of the planetary spin, which can notably lock a planet with a permanent night side. The atmospheric composition and mass depends on complex processes which are difficult to model: origins of volatile, atmospheric escape, geochemistry, photochemistry. We discuss physical constraints which can help us to speculate on the possible type of atmosphere, depending on the planet size, its final distance for its star and the star type. Assuming that the atmosphere is known, the possible climates can be explored using Global Climate Models analogous to the ones developed to simulate the Earth as well as the other telluric atmospheres in the solar system. Our experience with Mars, Titan and Venus suggests that realistic climate simulators can be developed by combining components like a "dynamical core", a radiative transfer solver, a parametrisation of subgrid-scale turbulence and convection, a thermal ground model, and a volatile phase change code. On this basis, we can aspire to build reliable climate predictors for exoplanets. However, whatever the accuracy of the models, predicting the actual climate regime on a specific planet will remain challenging because climate systems are affected by strong positive destabilizing feedbacks (such as runaway glaciations and runaway greenhouse effect). They can drive planets with very similar forcing and volatile inventory to completely different states.Comment: In press, Proceedings of the Royal Society A 31 pages, 6 figure

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“…However, the microphysical schemes of these models tend to ignore the nucleation process and start the simulation with a prescribed distribution of cloud condensation nuclei, which are assumed to be either ethane ice precipitating from the lower stratosphere (Samuelson & Mayo 1997), tholin from the middle and upper atmospheres (Rannou et al 2004, or a combination of both (Barth and Toon 2003Barth & Rafkin 2007). No relevant laboratory validation was done until Wang et al (2010), who reported the formation of methane/nitrogen droplets in an aerosol chamber under a condition similar to that of Titan.…”

Section: Introductionmentioning

confidence: 99%

Methane-Nitrogen Binary Nucleation: A New Microphysical Mechanism for Cloud Formation in Titan's Atmosphere

Tsai

Liang

Chen

2012

ApJ

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It is known that clouds are present in the troposphere of Titan; however, their formation mechanism, particle size, and chemical composition remain poorly understood. In this study, a two-component (CH 4 and N 2 ) bin-microphysics model is developed and applied to simulate cloud formation in the troposphere of Titan. A new process, binary nucleation of particles from CH 4 and N 2 gases, is considered. The model is validated and calibrated by recent laboratory experiments that synthesize particle formation in Titan-like environments. Our model simulations show that cloud layers can be formed at about 20 km with a particle size ranging from one to several hundred μm and number concentration 10 −2 to over 100 cm −3 depending on the strength of the vertical updraft. The particles are formed by binary nucleation and grow via the condensation of both CH 4 and N 2 gases, with their N 2 mole fraction varying from <10% in the nucleation stage to >30% in the condensation growth stage. The locally occurring CH 4 -N 2 binary nucleation mechanism is strong and could potentially be more important than the falling condensation nuclei mechanism assumed in many current models.

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A coupled dynamics-microphysics model of Titan's atmosphere

Cited by 117 publications

References 45 publications

Titan's stratospheric zonal wind, temperature, and ethane abundance a year prior to Huygens insertion

Titan's stratospheric zonal wind, temperature, and ethane abundance a year prior to Huygens insertion

Possible climates on terrestrial exoplanets

Methane-Nitrogen Binary Nucleation: A New Microphysical Mechanism for Cloud Formation in Titan's Atmosphere

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