Effects of magnetic anomalies discovered at Mars on the structure of the Martian ionosphere and solar wind interaction as follows from radio occultation experiments

Ness, N. F.; Acuña, M. H.; Connerney, J. E. P.; Kliore, A. J.; Бреус, Т. К.; Крымский, А. М.; Cloutier, P. A.; Bauer, S. J.

doi:10.1029/1999ja000212

Cited by 101 publications

(113 citation statements)

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“…One possible source of the enhanced neutral density is the heating and sputtering of the atmosphere by the precipitating magnetosheath plasma. The heating would elevate the altitude of the exobase and increase the exospheric scale height and thus locally increase the exospheric density above the IMB [Ness et al, 2000;Krymskii et al, 2004]. However, these enhancements are expected to be negligible since the local cusp regions are much smaller in comparison to the total area of the magnetic anomalies [Brain et al, 2007], and instances of large scale heights are rare according to radio occultation observations [Ness et al, 2000].…”

Section: Discussionmentioning

confidence: 99%

“…The heating would elevate the altitude of the exobase and increase the exospheric scale height and thus locally increase the exospheric density above the IMB [Ness et al, 2000;Krymskii et al, 2004]. However, these enhancements are expected to be negligible since the local cusp regions are much smaller in comparison to the total area of the magnetic anomalies [Brain et al, 2007], and instances of large scale heights are rare according to radio occultation observations [Ness et al, 2000]. Enhancements of the neutral density due to sputtering are also expected to be negligible for nominal solar conditions at Mars [Johnson et al, 2008;Wang et al, 2014].…”

Section: Discussionmentioning

confidence: 99%

“…The magnetic anomalies locally change the plasma flow of the shocked solar wind, which has been observed on numerous occasions. For example, the magnetic anomalies form the minimagnetosphere and cusp-like fields respectively in the closed and open field line regions [Mitchell et al, 2001;Ness et al, 2000;Krymskii et al, 2002]. They also elevate the induced magnetosphere boundary (IMB) Brain et al, 2005;Dubinin et al, 2006].…”

Section: Introductionmentioning

confidence: 99%

“…They also elevate the induced magnetosphere boundary (IMB) Brain et al, 2005;Dubinin et al, 2006]. Moreover, the magnetic anomalies allow the magnetosheath electrons to precipitate in the cusp-like regions [Ness et al, 2000;Krymskii et al, 2002;Soobiah et al, 2006] and restrict the vertical diffusion of ionospheric electrons in the closed field line regions [Soobiah et al, 2006;Brain et al, 2007]. The parameters and/or chemical states of the neutral atmosphere over the magnetic anomalies could be influenced by the varied plasma flux.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Martian crustal magnetic anomalies on the emission of energetic neutral hydrogen atoms

et al. 2014

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We analyze the data on hydrogen energetic neutral atoms (ENAs) emissions from the dayside of Mars, recorded by a Neutral Particle Detector of the Analyzer of Space Plasmas and Energetic Atoms aboard Mars Express from 14 March to 9 July 2004. We first identify and analyze events of the ENA flux enhancement coinciding with the presence of the crustal magnetic anomalies on the dayside of Mars. We then backtrace the ENA emissions to the lower altitudes (source region) and build up an average map of the flux intensities in the geographic coordinates with all the available data. The map shows a peak-to-valley ENA flux enhancement of 40%-90% close to the crustal magnetic anomaly regions. These results suggest the influence of the magnetic anomalies on the ENA emission from the dayside of Mars. The enhancement may result from the deviation of the highly directional plasma flow above anomalies toward the detectors such that more charge exchange ENAs would be recorded. Alternatively, higher exospheric densities above the anomalies would also result in an increase of the charge exchange ENA flux.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Martian crustal magnetic anomalies on the emission of energetic neutral hydrogen atoms

et al. 2014

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“…In the topside, they have interpreted the lack of distinctive ionopause features at the top of the ionosphere in terms of pressure balance with the solar wind (Kliore 1992;Luhmann 1992;Luhmann et al 1990;Shinagawa 1996;Slavin and Holzer 1982;Zhang and Luhmann 1992). They have noted that the morphology of the topside ionosphere can be described by an exponential decay in electron density with altitude, where the relevant scale height is uniform with altitude (Breus et al 1998;Kliore 1992;Ness et al 2000;Shinagawa 1996;Slavin and Holzer 1982). They have shown that the topside plasma scale height increases with increasing solar irradiance (Bauer and Hantsch 1989;Fjeldbo et al 1977;Ness et al 2000;Shinagawa 1996;Stewart and Hanson 1982).…”

Section: Introductionmentioning

confidence: 99%

Recovery and validation of Mars ionospheric electron density profiles from Mariner 9

2015

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Electron density profiles from the ionosphere of Mars that were obtained by the Mariner 9 radio occultation experiment in 1971-1972 have unique scientific value because they extend to higher altitudes than comparable datasets and were acquired during a tremendous dust storm that had substantial and poorly understood effects on the ionosphere. Yet these profiles are not publicly available in an accessible format. Here, we describe the recovery of these profiles, which are made available as part of this article. The validity of the profiles was tested by using them to explore the effects of a dust storm on the topside ionosphere, the morphology of the topside ionosphere, the behavior of the M1 layer, and possible meteoric layers. The dust storm that waned over the course of the primary mission (November-December 1971) had major effects on the ionosphere of Mars. It elevated the M1 and M2 layers of the ionosphere by 20-30 km, but the separation of the two layers stayed fixed throughout the primary mission, which suggests that the neutral atmosphere at these altitudes was not heated during the dust storm. However, the altitude of the 1500 cm −3 density level, a proxy for the top of the ionosphere, decreased steadily by 74 ± 12 km over the course of the primary mission. Mariner 9 observations of the topside ionosphere differ from comparable Mars Express observations. Compared to Mars Express, the Mariner 9 data, which were acquired during a period of relatively high solar wind dynamic pressure, have lower densities at high altitudes. They are also more likely to have a "one scale height" morphology than a "two scale height" morphology. The peak density of the M1 layer depends on solar zenith angle and solar irradiance similarly to previous studies with Mars Global Surveyor observations, which indicates that dust storms do not affect the behavior of the peak density. No clear meteoric layers were identified.

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Oblique reflections in the Mars Express MARSIS data set: Stable density structures in the Martian ionosphere

et al. 2014

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The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard theEuropean Space Agency's Mars Express (MEX) spacecraft routinely detects evidence of localized plasma density structures in the Martian dayside ionosphere. Such structures, likely taking the form of spatially extended elevations in the plasma density at a given altitude, give rise to oblique reflections in the Active Ionospheric Sounder data. These structures are likely related to the highly varied Martian crustal magnetic field. In this study we use the polar orbit of MEX to investigate the repeatability of the ionospheric structures producing these anomalous reflections, examining data taken in sequences of multiple orbits which pass over the same regions of the Martian surface under similar solar illuminations, within intervals lasting tens of days. Presenting three such examples, or case studies, we show for the first time that these oblique reflections are often incredibly stable, indicating that the underlying ionospheric structures are reliably reformed in the same locations and with qualitatively similar parameters. The visibility, or lack thereof, of a given oblique reflection on a single orbit can generally be attributed to variations in the crustal field within the ionosphere along the spacecraft trajectory. We show that, within these examples, oblique reflections are generally detected whenever the spacecraft passes over regions of intense near-radial crustal magnetic fields (i.e., with a "cusp-like" configuration). The apparent stability of these structures is an important feature that must be accounted for in models of their origin.

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Effects of magnetic anomalies discovered at Mars on the structure of the Martian ionosphere and solar wind interaction as follows from radio occultation experiments

Cited by 101 publications

References 33 publications

Influence of Martian crustal magnetic anomalies on the emission of energetic neutral hydrogen atoms

Influence of Martian crustal magnetic anomalies on the emission of energetic neutral hydrogen atoms

Recovery and validation of Mars ionospheric electron density profiles from Mariner 9

Oblique reflections in the Mars Express MARSIS data set: Stable density structures in the Martian ionosphere

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