DOI: 10.1029/2018JA025663
Scopus记录号: 2-s2.0-85052652721
论文题名: MARSIS Observations of Field-Aligned Irregularities and Ducted Radio Propagation in the Martian Ionosphere
作者: Andrews D.J. ; Opgenoorth H.J. ; Leyser T.B. ; Buchert S. ; Edberg N.J.T. ; Morgan D.D. ; Gurnett D.A. ; Kopf A.J. ; Fallows K. ; Withers P.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 8 起始页码: 6251
结束页码: 6263
语种: 英语
英文关键词: crustal fields
; ionosphere
; irregularities
; Mars
; MARSIS
; plasma
英文摘要: Knowledge of Mars's ionosphere has been significantly advanced in recent years by observations from Mars Express and lately Mars Atmosphere and Volatile EvolutioN. A topic of particular interest are the interactions between the planet's ionospheric plasma and its highly structured crustal magnetic fields and how these lead to the redistribution of plasma and affect the propagation of radio waves in the system. In this paper, we elucidate a possible relationship between two anomalous radar signatures previously reported in observations from the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument on Mars Express. Relatively uncommon observations of localized, extreme increases in the ionospheric peak density in regions of radial (cusp-like) magnetic fields and spread echo radar signatures are shown to be coincident with ducting of the same radar pulses at higher altitudes on the same field lines. We suggest that these two observations are both caused by a high electric field (perpendicular to B) having distinctly different effects in two altitude regimes. At lower altitudes, where ions are demagnetized and electrons magnetized, and recombination dominantes, a high electric field causes irregularities, plasma turbulence, electron heating, slower recombination, and ultimately enhanced plasma densities. However, at higher altitudes, where both ions and electrons are magnetized and atomic oxygen ions cannot recombine directly, the high electric field instead causes frictional heating, a faster production of molecular ions by charge exchange, and so a density decrease. The latter enables ducting of radar pulses on closed field lines, in an analogous fashion to interhemispheric ducting in the Earth's ionosphere. ©2018. 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/113338
Appears in Collections: 气候减缓与适应
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作者单位: Swedish Institute for Space Physics, Uppsala, Sweden; Department of Physics & Astronomy, University of Iowa, Iowa City, IA, United States; Center for Space Physics, Boston University, Boston, MA, United States; Department of Astronomy, Boston University, Boston, MA, United States
Recommended Citation:
Andrews D.J.,Opgenoorth H.J.,Leyser T.B.,et al. MARSIS Observations of Field-Aligned Irregularities and Ducted Radio Propagation in the Martian Ionosphere[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(8)