A survey of superthermal electron flux depressions, or "electron holes, " within the illuminated Martian induced magnetosphere. Issue 5 (26th May 2016)

• Record Type: Journal Article
• Authors: Hall, B. E. S.; Lester, M.; Nichols, J. D.; Sánchez‐Cano, B.; Andrews, D. J.; Opgenoorth, H. J.; Fränz, M.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 5(2016:May)
• Page Start: 4835
• Page End: 4857
• Publication Date: 2016-05-26
• Subjects: electron holes -- plasma void -- electron depression -- induced magnetosphere -- Mars' plasma environment -- Mars Express; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2015JA021866
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: Since Mars lacks a global intrinsic magnetic field, the solar wind interacts directly with the Martian upper atmosphere and ionosphere. The presence of localized intense remnant crustal magnetic fields adds to this interaction, making the Martian plasma system a unique environment within the solar system. Rapid reductions in the electron flux, referred to as "electron holes, " occur within the Martian induced magnetosphere (IM). We present a statistical analysis of this phenomenon identified from proxy measurements of the electron flux derived from measurements by the Analyser of Space Plasmas and Energetic Neutral Atoms Electron Spectrometer experiment on board the Mars Express (MEX) spacecraft. The study is completed for the period of 9 February 2004 to 9 May 2014. Electron holes are observed within the IM in more than 56% of MEX orbits during this study period, occurring predominantly at altitudes less than 1300 km, with the majority in the negative X Mars‐Centric Solar Orbital direction. The spatial distribution above the surface of Mars is observed to bear close resemblance to that of the crustal magnetic fields as predicted by the Cain et al . [2003 ] magnetic field model, suggesting that they play an important role in the formation of these phenomena. Key Points: Extreme reductions in proxy measurements of electron flux observed by MEX within illuminated induced magnetosphere Electron holes distributed near or over regions of significant crustal magnetic field magnitude At higher altitudes more events occur over regions of larger model crustal magnetic field magnitude