On the thermal structure of Triton's thermosphere

Michael H. Stevens, Darrell F. Strobel, Michael E. Summers, Roger Yelle

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

The analysis of the Voyager 2 Ultraviolet Spectrometer (UVS) solar occultation data obtained at Triton is consistent with a spherically symmetric, isothermal thermosphere above 400 km at T. = 96 K. A detailed calculation of energy loss processes in a pure N2 atmosphere, heating and cooling rates, and resultant thermal structure associated with solar UV irradiance and magnetospheric electron precipitation indicates that solar heating, with calculated T = 70 K, is insufficient to account for the inferred T = 96 K. The magnetosphere must deposit twice as much power as the sun (λ < 800 Å) to heat the thermosphere to 96 K and generate the observed N2 tangential column densities above 450 km. The thermal escape of H and N atoms and the downward diffusion of N atoms to recombine below 130 km results in local ionospheric heating efficiency of 24%. An upper limit on the tropopause CO mixing ratio of 2 × 10−4 is inferred in the absence of aerosol heating to balance its efficient cooling by LTE rotational line emission.

Original languageEnglish (US)
Pages (from-to)669-672
Number of pages4
JournalGeophysical Research Letters
Volume19
Issue number7
DOIs
StatePublished - 1992

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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