Influence of Extreme Ultraviolet Irradiance Variations on the Precipitating Ion Flux From MAVEN Observations

Antoine Martinez (1) , François Leblanc (1) , Jean-Yves Chaufray (1) , Ronan Modolo (1) , Olivier Witasse (2) , Y. Dong (3) , T. Hara (4) , J. Halekas (5) , R. Lillis (4) , J. Mcfadden (4) , F. Eparvier (5) , Ludivine Leclercq (6) , J. Luhmann (4) , S. Curry (4) , D. Titov (7) , B. Jakosky (5)

1 HELIOS - LATMOS
2 RSSD - Research and Scientific Support Department, ESTEC
3 LASP - Laboratory for Atmospheric and Space Physics [Boulder]
4 SSL - Space Sciences Laboratory [Berkeley]
5 Department of Physics and Astronomy [Iowa City]
6 MS - Department of Materials Science and Engineering [Charlottesville]
7 ESTEC - European Space Research and Technology Centre

We study the influence of the solar extreme ultraviolet (EUV) flux intensity on the precipitating ion fluxes as seen by the Solar Wind Ion Analyzer, an energy and angular ion spectrometer aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. We defined three periods with significantly different EUV flux intensity (1.6 and 3.2 times the lowest EUV intensity) and compare the precipitating ion flux measured by MAVEN/Solar Wind Ion Analyzer during each period. At low energy [30–650] eV, we find that the median (average) precipitating ion flux during the medium and low EUV periods are, respectively, 1.7 (2.1) and 3 (3.5) times more intense than the flux during the high EUV period. At high energy [650–25,000] eV, a similar trend in the intensity of the precipitating ion flux is observed but with an increase by 50% (46%) and 70% (79%), respectively. A larger EUV flux does therefore not seem to favor heavy ion precipitation into Mars's atmosphere, contrary to modeling prediction and overall expectations.

Domaines: Planète et Univers [physics]

Antoine Martinez, François Leblanc, Jean-Yves Chaufray, Ronan Modolo, Olivier Witasse, et al.. Influence of Extreme Ultraviolet Irradiance Variations on the Precipitating Ion Flux From MAVEN Observations. Geophysical Research Letters, 2019, 46 (13), pp.7761-7768. ⟨10.1029/2019GL083595⟩. ⟨insu-02182513⟩