Observations of Vertical Reflections from the Topside Martian Ionosphere

摘要: The Martian ionosphere has for the first time been probed by a low frequency topside radio wave sounder experiment (MARSIS) (Gurnett et al., 2005). density profiles in have observed solar zenith angles less than 48 degrees. spectrograms typically single trace of echoes, which are controlled reflections from direction nadir. With local at spacecraft derived measurements and using lamination technique inverted to electron profiles. yield sub-solar region past terminator. maximum varies with rotation period, indicating control densities ionizing radiation. Electron increases associated flares were observed. angle as predicted theory. altitude profile between about 170 km is well approximated classic Chapman layer. neutral scale height close 10 13 km. At altitudes above 180 deviate larger inferred exobase decrease was an exponential function heights 24 65 top side tends be extrapolated layer fitted lower altitudes, implying more efficient upward diffusion collision dominated photo equilibrium region.