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 e xperiments 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-Sur veyor (MGS) spacecraft show the existence of highly variable and very local ized magnetic fields of crustal origin at Mars. Addressing the difference b etween the ionosphere at Venus and Mars, the scale heights of electron dens ity profiles obtained by radio occultation methods onboard Mariner 9 and Vi king 1 are analyzed at altitudes higher than the topside boundary of the ph otoequlibrium region in the magnetic field-free ionosphere. The local incre ase of the mean scale height in the altitude region 180-250 km is assumed t o be either an effect of a nonhorizontal magnetic field associated with the magnetic anomalies or diffusive equilibrium in the magnetic field free ion osphere. The areas where the scale height of electron density profile,is in creased in comparison with average one have been selected. The angle betwee n the magnetic field measured by MGS MAG/ER at altitudes 120-250 km and loc al zenith direction is investigated throughout these selected areas.