On the thermal structure of Triton's thermosphere
Article first published online: 7 DEC 2012
Copyright 1992 by the American Geophysical Union.
Geophysical Research Letters
Volume 19, Issue 7, pages 669–672, 3 April 1992
How to Cite
- Issue published online: 7 DEC 2012
- Article first published online: 7 DEC 2012
- Manuscript Accepted: 16 JAN 1992
- Manuscript Received: 17 DEC 1991
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.