The Implications of 3D Thermal Structure on 1D Atmospheric Retrieval

Jasmina Blecic, Ian Dobbs-Dixon, Thomas Greene

    Research output: Contribution to journalArticle

    Abstract

    Using the atmospheric structure from a 3D global radiation-hydrodynamic simulation of HD 189733b and the open-source Bayesian Atmospheric Radiative Transfer (BART) code, we investigate the difference between the secondary-eclipse temperature structure produced with a 3D simulation and the best-fit 1D retrieved model. Synthetic data are generated by integrating the 3D models over the Spitzer, the Hubble Space Telescope (HST), and the James Web Space Telescope (JWST) bandpasses, covering the wavelength range between 1 and 11 μm where most spectroscopically active species have pronounced features. Using the data from different observing instruments, we present detailed comparisons between the temperature-pressure profiles recovered by BART and those from the 3D simulations. We calculate several averages of the 3D thermal structure and explore which particular thermal profile matches the retrieved temperature structure. We implement two temperature parameterizations that are commonly used in retrieval to investigate different thermal profile shapes. To assess which part of the thermal structure is best constrained by the data, we generate contribution functions for our theoretical model and each of our retrieved models. Our conclusions are strongly affected by the spectral resolution of the instruments included, their wavelength coverage, and the number of data points combined. We also see some limitations in each of the temperature parametrizations, as they are not able to fully match the complex curvatures that are usually produced in hydrodynamic simulations. The results show that our 1D retrieval is recovering a temperature and pressure profile that most closely matches the arithmetic average of the 3D thermal structure. When we use a higher resolution, more data points, and a parametrized temperature profile that allows more flexibility in the middle part of the atmosphere, we find a better match between the retrieved temperature and pressure profile and the arithmetic average. The Spitzer and HST simulated observations sample deep parts of the planetary atmosphere and provide fewer constraints on the temperature and pressure profile, while the JWST observations sample the middle part of the atmosphere, providing a good match with the middle and most complex part of the arithmetic average of the 3D temperature structure.

    Original languageEnglish (US)
    Article number127
    JournalAstrophysical Journal
    Volume848
    Issue number2
    DOIs
    StatePublished - Oct 20 2017

    Fingerprint

    thermal structure
    retrieval
    temperature profiles
    profiles
    temperature
    Hubble Space Telescope
    radiative transfer
    simulation
    hydrodynamics
    telescopes
    atmospheres
    planetary atmospheres
    Space Infrared Telescope Facility
    eclipses
    parameterization
    wavelengths
    spectral resolution
    wavelength
    atmospheric structure
    planetary atmosphere

    Keywords

    • methods: numerical
    • planets and satellites: atmospheres
    • planets and satellites: composition
    • planets and satellites: gaseous planets
    • planets and satellites: individual (HD 189733b)

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    The Implications of 3D Thermal Structure on 1D Atmospheric Retrieval. / Blecic, Jasmina; Dobbs-Dixon, Ian; Greene, Thomas.

    In: Astrophysical Journal, Vol. 848, No. 2, 127, 20.10.2017.

    Research output: Contribution to journalArticle

    Blecic, Jasmina ; Dobbs-Dixon, Ian ; Greene, Thomas. / The Implications of 3D Thermal Structure on 1D Atmospheric Retrieval. In: Astrophysical Journal. 2017 ; Vol. 848, No. 2.
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