Effects of magnetic anomalies discovered at Mars on the structure of the Martian ionosphere and solar wind interaction as follows from radio occultation experiments

The slopes of the electron density profiles obtained by radio occultation experiments at Mars revealed different variations with solar zenith angle in comparison with behavior of the electron density profiles in the magnetic field free ionosphere of Venus. The results obtained by the Mars‐Global‐Surveyor (MGS) spacecraft show the existence of highly variable and very localized magnetic fields of crustal origin at Mars. Addressing the difference between the ionosphere at Venus and Mars, the scale heights of electron density profiles obtained by radio occultation methods onboard Mariner 9 and Viking 1 are analyzed at altitudes higher than the topside boundary of the photoequlibrium region in the magnetic field‐free ionosphere. The local increase of the mean scale height in the altitude region 180–250 km is assumed to be either an effect of a nonhorizontal magnetic field associated with the magnetic anomalies or diffusive equilibrium in the magnetic field free ionosphere. The areas where the scale height of electron density profile is increased in comparison with average one have been selected. The angle between the magnetic field measured by MGS MAG/ER at altitudes 120–250 km and local zenith direction is investigated throughout these selected areas.