Summary: tCARUS 24, 358--:~62 (1975)
Ionospheric Models of Saturn, Uranus, and Neptune
S. K. ATREYA t AND T. M. DONAHUE ~
Department of Physics, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
Received September 6, 1974; revised November 4, 1974
Model ionospheres are calculated for Saturn, Uranus, and Neptune. Protons
are the maj or ions above 150 km altitude measured from a reference levelwhere the
hydrogen density is 1 × 1016 molecules cm-a, while below 150 km quick conversion
of protons to Ha + ions by a three-body association mechanism leads to a rapid
removal of ionization in dissociative recombination of Ha +. Electron density
maxima are found at about 260 km for Saturn and Uranus and 200 km for Neptune.
Present knowledge of the physical and chemical processes in the atmospheres of
these planets suggests that their ionospheres probably will not be Jupiter-like.
The Pioneer l0 radio occultation experi-
ment has provided the first direct measure-
ment of the electron density profile in the
ionosphere of Jupiter (Kliore et al., 1974).
The magnitude and location ofthe principal
maximum in the electron density profile