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Modelling H3+ in planetary atmospheres: effects of vertical gradients on observed quantities.
Moore, L; Melin, H; O'Donoghue, J; Stallard, T S; Moses, J I; Galand, M; Miller, S; Schmidt, C A.
Afiliação
  • Moore L; Boston University, Boston, MA, USA.
  • Melin H; University of Leicester, Leicester, UK.
  • O'Donoghue J; NASA Goddard Space Flight Center, Greenbelt, MD, USA.
  • Stallard TS; University of Leicester, Leicester, UK.
  • Moses JI; Space Science Institute, Boulder, CO, USA.
  • Galand M; Department of Physics, Imperial College London, London, UK.
  • Miller S; University College London, London, UK.
  • Schmidt CA; Boston University, Boston, MA, USA.
Philos Trans A Math Phys Eng Sci ; 377(2154): 20190067, 2019 Sep 23.
Article em En | MEDLINE | ID: mdl-31378180
Since its detection in the aurorae of Jupiter approximately 30 years ago, the H3+ ion has served as an invaluable probe of giant planet upper atmospheres. However, the vast majority of monitoring of planetary H3+ radiation has followed from observations that rely on deriving parameters from column-integrated paths through the emitting layer. Here, we investigate the effects of density and temperature gradients along such paths on the measured H3+ spectrum and its resulting interpretation. In a non-isothermal atmosphere, H3+ column densities retrieved from such observations are found to represent a lower limit, reduced by 20% or more from the true atmospheric value. Global simulations of Uranus' ionosphere reveal that measured H3+ temperature variations are often attributable to well-understood solar zenith angle effects rather than indications of real atmospheric variability. Finally, based on these insights, a preliminary method of deriving vertical temperature structure is demonstrated at Jupiter using model reproductions of electron density and H3+ measurements. The sheer diversity and uncertainty of conditions in planetary atmospheres prohibits this work from providing blanket quantitative correction factors; nonetheless, we illustrate a few simple ways in which the already formidable utility of H3+ observations in understanding planetary atmospheres can be enhanced. This article is part of a discussion meeting issue 'Advances in hydrogen molecular ions: H3+, H5+ and beyond'.
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Texto completo: 1 Base de dados: MEDLINE Tipo de estudo: Prognostic_studies Idioma: En Ano de publicação: 2019 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Tipo de estudo: Prognostic_studies Idioma: En Ano de publicação: 2019 Tipo de documento: Article