Studies of Jupiter's lower ionospheric layers

Theoretical calculations are made of the fluxes of heavy ions necessary to form the layers of enhanced ionization observed in the lower ionosphere of Jupiter. The results show that if the layers are formed from sodium or sulfur ions of Galilean satellite origin injected into the Jovian atmosphere then, in order to match the Pioneer 10 observations of the L6 layer, the Na+ flux must be about 3 × 104 cm−2 s−1 and the S+ flux must be about 4 × 10³ cm−2 s−1. From the shape of the ionization layers estimates of ion drift velocities and neutral wind speeds may be made. The vertical ion drift velocities range from a few centimeters per second to meters per second while the zonal wind shear ranges from 50 m/s westward to 200 m/s eastward over a 70 km altitude range and small (centimeters per second) meridional winds are sufficient to form the layers.