Martian ionosphere observed by Mars Express. 2. Influence of solar irradiance on upper ionosphere and escape fluxes. (1st October 2017)

• Record Type: Journal Article
• Authors: Dubinin, E.; Fraenz, M.; Pätzold, M.; Andrews, D.; Vaisberg, O.; Zelenyi, L.; Barabash, S.
• Is Part Of: Planetary and space science. Volume 145(2017)
• Page Start: 1
• Page End: 8
• Publication Date: 2017-10-01
• Subjects: Mars -- Solar irradiance -- Ionosphere -- Mars express -- Escape; Space sciences -- Periodicals; Atmosphere, Upper -- Periodicals; Sciences spatiales -- Périodiques; Haute atmosphère -- Périodiques; 523
• DOI: 10.1016/j.pss.2017.07.002
• Languages: English
• ISSNs: 0032-0633

Abstract

Abstract: We present multi-instrument observations of the effects of solar irradiance on the upper Martian ionosphere and escape fluxes based on Mars Express measurements obtained over almost 12 years. It is shown that the variations in the upper ionosphere caused by solar irradiance lead to significant changes in the trans -terminator fluxes of low-energy ions and total ion losses through the tail. The observed dependence of the electron number density in the upper ionosphere at altitudes above 300 km on solar irradiance implies that the ionosphere at such altitudes was denser by a factor of ten during the periods of solar maxima in solar cycles 22–23. Correspondingly, the trans -terminator fluxes of cold ions and escape fluxes through the tail were also significantly higher. We estimate an increase of total ion losses through the tail during these solar maxima by a factor of 5–6. Highlights: Mars Express surveyed effects of solar irradiance on the Martian ionosphere and ion escape during more than 12 years. Variations in EUV flux cause significant changes in the upper ionosphere. The ionosphere expands and becomes denser with the EUV increasse. Trans-terminator and tail fluxes of cold-energy oxygen ions also become significantly higher with the enhancement of solar irradiance.