H₂ vibrational temperatures in the upper atmosphere of Jupiter

¹ Laboratoire de Planétologie de Grenoble, CNRS - UJF, BP 53, 38041 Saint-Martin-d'Hères, Cedex 9, France e-mail: mathieu.barthelemy@ujf-grenoble.fr
² MS 150-21, Caltech, Pasadena, California, 91125, USA e-mail: cdp@gps.caltech.edu
³ MS 183-501, JPL, Pasadena, California, 9110, USA

Received: 12 February 2004
Accepted: 18 March 2005

Abstract

The Jovian upper atmosphere has been extensively studied over the past few decades with many observations having been made. Typically, the H₂ vibrational temperatures have always been considered as kinetic temperatures in modelling efforts to date. However, recent studies have shown that this assumption is not robust and that we can expect enhanced vibrational temperatures due to overlapping lines to play an important role in the thermosphere of Jupiter. In this paper, we use a radiative transfer code to compute the total integrated H Lyman α dayglow intensity taking into account the overlapping with H₂ hot bands. We show that an atmosphere with H₂ vibrational temperatures equal to about 1.4 to 1.5 times kinetic reproduce the Voyager observations.