A model of the Venus ionosphere

Results of model calculations of the Venus ionosphere covering the altitude range from 120 km to 300 km are presented. The chemical scheme and the reaction rates adopted for the model are the same as given in a recent paper by Kumar and Hunten [1974], except that the electron temperature dependence of the dissociative recombination rates is taken into account. The calculations were carried out for ‘low’ and ‘high’ atomic oxygen models, corresponding to an [O]/[CO2] ratio of 0.4 percent and 4 percent respectively at 140 km. The results of the calculations agree well in both shape and magnitude with the Mariner 5 and 10 occultation results in the chemically controlled region; at the higher altitudes reasonable agreement with the observation is obtained if diffusive equilibrium and high vertical flow velocities (10 km/sec) are assumed as upper boundaries for the Mariner 5 and 10 conditions, respectively, although solar wind‐ionosphere interactions are the likely controlling mechanism for the Mariner 10 case.