The variability of the topside ionosphere of Mars characterized from Mars Express and MAVEN observations

• Applicant: Privatdozent Dr. Martin Pätzold
• Subject Area: Astrophysics and Astronomy
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 533053701

The topside ionosphere of Mars, the region above the altitude of the peak plasma density of the main layer M2 typically located at 140 km, is very dynamic. It often shows either multi-ionospheric layers or sharp ionopause structures in electron density profiles observed by MARSIS, the Mars Express ground penetrating radar, or by the radio science experiment MaRS, respectively. Sometimes the top-side ionosphere is very wavy indicating either excitation of the internal ionospheric instabilities or transport of solar wind disturbances downwards or upward propagating waves from the lower atmosphere. The ion and electron temperatures in the topside ionosphere are higher than those predicted by photochemical models implying the existence of additional heating. The topside ionosphere above thoseregions with strong local magnetization in the southern hemisphere is different then that in the northern hemisphere and may contain ionospheric holes or ionization patches. The dynamics of the topside ionosphere of Mars is subject of temporal variability by external (solar wind, interplanetary magnetic field, space weather events) and internal (crustal magnetic field, thermosphere winds, waves, dust events) drivers and therefore multi-instrument observations shall be used for the investigation of these phenomena. A dual-spacecraft, Mars Express and MAVEN, and multi-instrument data analysis of the topside ionosphere of Mars is proposed. The observations of the Mars Express (12/2003-ongoing) and MAVEN (09/2014-ongoing) spacecraft at Mars provide unique opportunities for a deeper understanding and explanation of the physical mechanisms which are responsible for the variety of the phenomena observed in the Martian topside ionosphere.

• DFG Programme: Research Grants