Empirical Model of the Martian Dayside Ionosphere: Effects of Crustal Magnetic Fields and Ionizing Flux at Higher Altitudes

We use electron density profiles measured by the MARSIS instrument on boardthe Mars Express spacecraft to investigate the effects of possible controllingparameters unconsidered in the empirical model of Nemec et al. (2011).Specifically, we focus on the effects of crustal magnetic fields and F10.7proxy of the ionizing flux at higher altitudes. It is shown that while the peakdensity and altitude are nearly unaffected by crustal magnetic fields, electrondensities at higher altitudes are significantly increased in areas of strongermagnetic fields. Moreover, while the empirical model accounted for the variableionizing flux at low altitudes, the high altitude diffusive region wasparameterized only by the solar zenith angle and the altitude. It is shown thatthis can lead to considerable inaccuracies. A simple correction of the previousmodel, which takes into account both these effects, is suggested.