Meteoric Ions in the Ionosphere of Jupiter

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A recent analysis of the Voyager 2 radio occultation data revealed a low- altitude ionospheric layer in Jupiter. A peak electron density at the layer is inferred to be on the order of 104 cm-3 at predawn, which is much larger than that of a hydrocarbon ion layer in our ionospheric model (Kim and Fox, Icarus, 112, 310, 1994). The large electron density at predawn indicates the existence of long lifetime ions, such as atomic ions originated from meteoroid ablation in Jupiter's atmosphere. We have modeled the chemistry of meteoric ions, namely, Si+, Fe+, Mg+, Na+, S+, in Jupiter's ionosphere. The neutral and ion compounds of the meteoric elements are also included in the calculation of production and loss of the meteoric ions. The model shows a layer of meteoric ions in the altitude region of 300 - 500 km with densities comparable to the observed electron density. The peak of the layer are located higher than the hydrocarbon ion layer at daytime. This feature is due to three body reactions of meteoric atomic ions with hydrocarbon molecules, resulting in molecular ions that can recombine with electrons fast. This sort of reaction processes has not been included in previous meteoric ion models for outer planets. Detailed production and loss processes of the meteoric ions will be presented. The uncertainties in reaction rate coefficients and their effects on meteoric ion densities in Jupiter's ionosphere will be discussed.


Presented at the 1998 Fall Meeting of the American Geophysical Union (AGU), San Francisco, CA.

Presentation Number SA11A-01.

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