Double-Peak Structures of Martian Nightside Total Electron Content in Strong Crustal Magnetic Cusp Regions

With the help of the high-spatial-resolution total electron content (TEC) data obtained by Mars Advanced Radar for Subsurface and Ionospheric Sounding on board the Mars Express (MEx) during June 2005 to September 2007, the detailed configurations of the Martian nightside ionosphere in crustal magnetic field cusp regions are researched in this paper. It is found that double-peak structures of orbital observed TEC values frequently appeared when MEx was crossing through the strong crustal magnetic field cusp regions. This observational result implies that the Martian nightside TECs in the periphery of the cusp regions are generally higher than those in the central areas of the cusp regions, a phenomenon never reported before. By combining the TEC data with the in-situ electron flux data obtained by the Analyzer of Space Plasma and Energetic Atoms-3 (ASPERA-3), it is found that the difference between the fluxes of the electrons precipitating in the central and peripheral areas of the cusp regions can be responsible for the observed TEC double-peak structures.

Automated summary

This study investigates the detailed configurations of the Martian nightside ionosphere in crustal magnetic field cusp regions using high-spatial-resolution total electron content (TEC) data obtained by Mars Advanced Radar for Subsurface and Ionospheric Sounding. It finds that the double-peak structures of TEC values are frequently observed in strong crustal magnetic field cusp regions, with higher TECs in the periphery than in the central areas. The difference in electron fluxes precipitating in central and peripheral areas of the cusp regions is responsible for the observed TEC double-peak structures.