Solar wind modulation of the Martian ionosphere observed by Mars Global Surveyor

Wang, J.-S.; Nielsen, E.

doi:10.5194/angeo-22-2277-2004

Cited by 9 publications

(6 citation statements)

References 19 publications

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“…(7) and (8); Fox and Yeager, 2009). In addition, Wang and Nielsen (2004b) have adduced evidence that the interaction of solar wind protons with the martian thermosphere increases the temperature at thermospheric altitudes, and raises the altitude of the F 1 peak. The E peaks have been found to be greatly enhanced in the presence of solar flares, which occur more often at high than at low solar activity (e.g., Mendillo et al, 2006;Haider et al, 2009).…”

Section: Peak Altitudesmentioning

confidence: 97%

MGS electron density profiles: Analysis and modeling of peak altitudes

Fox

Weber

2012

Icarus

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Section: Peak Altitudesmentioning

confidence: 97%

MGS electron density profiles: Analysis and modeling of peak altitudes

Fox

Weber

2012

Icarus

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“…Finally, the results of the same analysis for the altitude of peak electron density z m are shown in Figure 5. Since the altitude of the ionospheric peak, unlike the peak electron density, is not very sensitive to a change of the neutral scale height above the ionospheric peak [ Wang and Nielsen , 2004] and, moreover, seems to express reasonably well the dependence observed in the data, no additional correction was introduced to the original Chapman theory regarding the parameter z m . It is assumed that the dependence follows with the value of H = H 0 .…”

Section: Chapman Regionmentioning

confidence: 99%

Dayside ionosphere of Mars: Empirical model based on data from the MARSIS instrument

et al. 2011

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[1] We present results of a systematic study of electron densities in the dayside Martian ionosphere measured by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on board the Mars Express spacecraft. There are two distinct regions controlled by different physical mechanisms. The first region is located at altitudes up to about 5 neutral scale heights above the altitude of peak electron density. Electron densities in this region are well described by the basic Chapman theory. The observed small deviations can be most probably explained by the neutral scale height and electron temperature increasing with altitude rather than being constant. The second region is located at altitudes higher than about 10 neutral scale heights above the altitude of peak electron density. It is controlled primarily by diffusion, and the observed electron densities decrease exponentially with increasing altitude. The corresponding diffusion scale height increases with increasing solar zenith angle, which can be probably explained by nearly horizontal magnetic fields in the ionosphere induced by interaction with the solar wind. The obtained dependencies can be used as a simple empirical model of the dayside Martian ionosphere.

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“…Apart from solar zenith angle effects, there may be further spatial variations owing to crustal magnetic fields (Nagy et al, 2004). However, at higher altitudes, above the photo chemical equilibrium region, vertical diffusion and horizontal plasma transport processes as well as plasma wave activity induced owing to planet rotation, magnetic fields, and solar wind interactions lead to modifications of the plasma at Mars (Luhman et al, 1992;Shinagawa, 2000;Acuna et al, 1998Acuna et al, , 1999Ness et al, 2000;Wang and Nielsen, 2004).…”

Section: Introductionmentioning

confidence: 97%

Observations of Vertical Reflections from the Topside Martian Ionosphere

et al. 2006

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The Martian ionosphere has for the first time been probed by a low frequency topside radio wave sounder experiment (MARSIS) (Gurnett et al., 2005). The density profiles in the Martian ionosphere have for the first time been observed for solar zenith angles less than 48 degrees. The sounder spectrograms typically have a single trace of echoes, which are controlled by reflections from the ionosphere in the direction of nadir. With the local density at the spacecraft derived from the sounder measurements and using the lamination technique the spectrograms are inverted to electron density profiles. The measurements yield electron density profiles from the sub-solar region to past the terminator. The maximum density varies in time with the solar rotation period, indicating control of the densities by solar ionizing radiation. Electron density increases associated with solar flares were observed. The maximum electron density varies with solar zenith angle as predicted by theory. The altitude profile of electron densities between the maximum density and about 170 km altitude is well approximated by a classic Chapman layer. The neutral scale height is close to 10 to 13 km. At altitudes above 180 km the densities deviate from and are larger than inferred by the Chapman layer. At altitudes above the exobase the density decrease was approximated by an exponential function with scale heights between 24 and 65 km. The densities in the top side ionosphere above the exobase tends to be larger than the densities extrapolated from the Chapman layer fitted to the measurements at lower altitudes, implying more efficient upward diffusion above the collision dominated photo equilibrium region.

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Solar wind modulation of the Martian ionosphere observed by Mars Global Surveyor

Cited by 9 publications

References 19 publications

MGS electron density profiles: Analysis and modeling of peak altitudes

MGS electron density profiles: Analysis and modeling of peak altitudes

Dayside ionosphere of Mars: Empirical model based on data from the MARSIS instrument

Observations of Vertical Reflections from the Topside Martian Ionosphere

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