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Préparation et analyses des observations de l'atmosphère et des glaces de Pluton par la mission NASA New Horizons à l'aide de modèles numériques de climat

Abstract : On July 14, 2015, the New Horizons spacecraft flew by Pluto and revealed an active frozen world.These observations call upon modelling efforts to complete their analysis and understand the mechanisms at play on Pluto. For this purpose, we have developed two numerical models of Pluto’s climate: a 2D model dedicated to the study of Pluto’s surface and a 3D model of Pluto’s atmosphere. We analyse the annual and paleoclimatic volatile cycles. Our simulations reproduce the distribution of the volatile observed on Pluto’s surface and their abundance in the atmosphere. We show that the solar insolation on Pluto and the nature of its atmosphere favour the condensation of nitrogen in the Sputnik Planitia basin, as observed. We simulate the glacial activity of the Sputnik Planitia ice cap on a timescale of millions of years, as well as the formation of methane glaciers at the equator. Our results are in agreement with the observations. We then focus on Pluto’s atmosphere in 2015 with the full 3D model where we performed a comprehensive characterization of the atmosphere: wind regimes, cloud formation, temperatures etc. ...We demonstrate the sensitivity of the general circulation to the distribution of the nitrogen ice on the surface and show that Pluto’s atmosphere currently undergoes retrograde rotation, induced by the condensation-sublimation of nitrogen in Sputnik Planitia. We also show that several phenomena originate at the cold boundary layer observed deep in Sputnik Planitia. Finally, by reproducing the processes that lead to the formation of organic haze, we simulate haze transport in the atmosphere and explain the greater extension of the haze observed at the north pole.
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https://tel.archives-ouvertes.fr/tel-01746075
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Submitted on : Friday, April 20, 2018 - 3:45:15 AM
Last modification on : Tuesday, September 22, 2020 - 3:46:44 AM
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2017PA066243.pdf
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  • HAL Id : tel-01746075, version 2

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Tanguy Bertrand. Préparation et analyses des observations de l'atmosphère et des glaces de Pluton par la mission NASA New Horizons à l'aide de modèles numériques de climat. Astrophysique [astro-ph]. Université Pierre et Marie Curie - Paris VI, 2017. Français. ⟨NNT : 2017PA066243⟩. ⟨tel-01746075v2⟩

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