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MARSIS Observations...
MARSIS Observations of Field-Aligned Irregularities and Ducted Radio Propagation in the Martian Ionosphere
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- Andrews, David J. (author)
- Uppsala universitet,Institutet för rymdfysik, Uppsalaavdelningen
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- Opgenoorth, Hermann J. (author)
- Uppsala universitet,Institutet för rymdfysik, Uppsalaavdelningen
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- Leyser, Thomas B. (author)
- Uppsala universitet,Institutet för rymdfysik, Uppsalaavdelningen
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- Buchert, Stephan (author)
- Uppsala universitet,Institutet för rymdfysik, Uppsalaavdelningen
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- Edberg, Niklas J. T. (author)
- Uppsala universitet,Institutet för rymdfysik, Uppsalaavdelningen
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- Morgan, D. D. (author)
- Univ Iowa, Dept Phys & Astron, Iowa City, IA USA
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- Gurnett, D. A. (author)
- Univ Iowa, Dept Phys & Astron, Iowa City, IA USA
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- Kopf, A. J. (author)
- Univ Iowa, Dept Phys & Astron, Iowa City, IA USA
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- Fallows, K. (author)
- Boston Univ, Ctr Space Phys, Boston, MA USA
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- Withers, P. (author)
- Boston Univ, Ctr Space Phys, Boston, MA USA; Boston Univ, Dept Astron, Commonwealth Ave, Boston, MA USA
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(creator_code:org_t)
- 2018
- 2018
- English.
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In: Journal of Geophysical Research - Space Physics. - 2169-9380 .- 2169-9402. ; 123:8, s. 6251-6263
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
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- 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.
Subject headings
- NATURVETENSKAP -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Keyword
- Mars
- ionosphere
- irregularities
- MARSIS
- crustal fields
- plasma
Publication and Content Type
- ref (subject category)
- art (subject category)
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Andrews, David J ...
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Opgenoorth, Herm ...
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Leyser, Thomas B ...
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Buchert, Stephan
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Edberg, Niklas J ...
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Morgan, D. D.
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show more...
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Gurnett, D. A.
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Kopf, A. J.
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Fallows, K.
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Withers, P.
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Physical Science ...
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and Fusion Plasma an ...
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NATURAL SCIENCES
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and Physical Science ...
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Uppsala University