DOI: 10.1002/2017JE005395
Scopus记录号: 2-s2.0-85040174527
论文题名: Field-Aligned Electrostatic Potentials Above the Martian Exobase From MGS Electron Reflectometry: Structure and Variability
作者: Lillis R.J. ; Halekas J.S. ; Fillingim M.O. ; Poppe A.R. ; Collinson G. ; Brain D.A. ; Mitchell D.L.
刊名: Journal of Geophysical Research: Planets
ISSN: 21699097
出版年: 2018
卷: 123, 期: 1 起始页码: 67
结束页码: 92
语种: 英语
英文关键词: electric
; field
; magnetic
; Mars
; MGS
; parallel
Scopus关键词: magnetic field
; magnetometer
; Martian atmosphere
; solar wind
英文摘要: Field-aligned electrostatic potentials in the Martian ionosphere play potentially important roles in maintaining current systems, driving atmospheric escape and producing aurora. The strength and polarity of the potential difference between the observation altitude and the exobase (~180 km) determine the energy dependence of electron pitch angle distributions (PADs) measured on open magnetic field lines (i.e. those connected both to the collisional atmosphere and to the interplanetary magnetic field). Here we derive and examine a data set of ~3.6 million measurements of the potential between 185 km and 400 km altitude from PADs measured by the Mars Global Surveyor Magnetometer/Electron Reflectometer experiment at 2 A.M./2 P.M. local time from May 1999 to November 2006. Potentials display significant variability, consistent with expected variable positive and negative divergences of the convection electric field in the highly variable and dynamic Martian plasma environment. However, superimposed on this variability are persistent patterns whereby potential magnitudes depend positively on crustal magnetic field strength, being close to zero where crustal fields are weak or nonexistent. Average potentials are typically positive near the center of topologically open crustal field regions where field lines are steeper, and negative near the edges of such regions where fields are shallower, near the boundaries with closed fields. This structure is less pronounced for higher solar wind pressures and (on the dayside) higher solar EUV irradiance. Its causes are uncertain at present but may be due to differential motion of electrons and ions in Mars's substantial but (compared to Earth) weak magnetic fields. ©2017. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/114879
Appears in Collections: 气候减缓与适应
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作者单位: Space Sciences Laboratory, University of California Berkeley, Berkeley, CA, United States; Department of Physics and Astronomy, University of Iowa, Iowa city, IA, United States; NASA Goddard Space Flight Center, Greenbelt, MD, United States; Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States
Recommended Citation:
Lillis R.J.,Halekas J.S.,Fillingim M.O.,et al. Field-Aligned Electrostatic Potentials Above the Martian Exobase From MGS Electron Reflectometry: Structure and Variability[J]. Journal of Geophysical Research: Planets,2018-01-01,123(1)