An investigation on the variations of dayside and nightside electron densities of the Martian ionosphere

In this study, electron density data from Langmuir Probe and Waves (LPW) instrument onboard MAVEN are used to investigate the variations of the Martian ionosphere with Solar Zenith Angle (SZA) and the day-night difference of electron density. By analyzing electron density data during 2014-2017, we found that, the photochemical process is more important than the transport process below 200 km, and the day-night plasma transport can affect the electron density at SZA < 110 degrees. For the region above 200 km, the transport process can greatly affect the structure of the topside ionosphere, and the day-night difference of electron densities is much smaller than that below 200 km, and electron density decreases gradually with increasing SZA. In addition, we analyzed the electron density data during MAVEN's deep-dip campaigns. It was found that the strong geomagnetic fields in the southern hemisphere could affect the electron density at night. The closed geomagnetic lines might obstruct the electron precipitating process and cause a decrease in electron density as compared with surrounding regions. By comparing the electron density profiles during the deep-dip campaigns, it was found that the precipitation electrons probably affect the electron density below 160 km at night.