Effects of Martian crustal magnetic field on its ionosphere

Zou, Hong; Chen, Hongfei; Yu, Ning; Shi, Wankai; Yu, X. D.; Zou, Jingxian; Zhong, WeiYing

doi:10.1007/s11431-010-3118-1

Cited by 8 publications

(5 citation statements)

References 37 publications

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“…The dependences of the peak electron density on solar radiation [ Stewart and Hanson , 1982; Breus et al , 2004; Zou et al , 2006; Fox and Yeager , 2009; Withers , 2009], solar zenith angle [ Hantsch and Bauer , 1990; Zhang et al , 1990; Gurnett et al , 2005; Fox and Yeager , 2009; Withers , 2009], and solar cycle [ Bauer and Hantsch , 1989] generally agree with the expectation for a Chapman layer‐like ionosphere. Effects from other influences, such as magnetic field [ Krymskii et al , 1995, 2002, 2003, 2004; Breus et al , 2004; Nielsen et al , 2007; Zou et al , 2010], are left for approaches other than Chapman theory.…”

Section: Introductionmentioning

confidence: 99%

Determination of seasonal variations in the Martian neutral atmosphere from observations of ionospheric peak height

et al. 2011

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[1] Radio occultation experiments allow us to measure electron and neutral densities in planetary atmospheres. Here we investigate such measurements from the Mars Global Surveyor Radio Science experiment in 2 consecutive Martian years (25 and 26). Using Chapman theory, we parameterize the ionospheric peak altitude in terms of the solar zenith angle, neutral scale height at the peak, neutral density at 20 km and the effective neutral scale height ( n ) between 20 km and the peak, finding the latter to be the primary driver of peak altitude. From the occultation data, we observe that altitudes of peak electron density at high northern latitudes show a clear seasonal trend, increasing from northern summer (Ls = 90°) to northern autumn (Ls = 180°), driven by substantial increases in n , despite neutral densities at 20 km steadily decreasing as surface temperatures drop. We find these trends to be consistent with neutral density predictions from the LMD Mars Global Circulation Model at both 20 km and 130 km. The primary mechanism responsible for this increase in the 20-130 km effective neutral scale height (and hence temperature) is the southward drift in subsolar latitude as northern summer becomes autumn. This drives the seasonal evolution of the Martian interhemispheric Hadley circulation. The downward branch of this circulation leads to an increasing warming in the middle atmosphere at high north latitudes from the northern summer to the northern autumn, causing an increase in neutral scale height at and below the ionospheric peak and thus an increase in the ionospheric peak height.

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Section: Introductionmentioning

confidence: 99%

Determination of seasonal variations in the Martian neutral atmosphere from observations of ionospheric peak height

et al. 2011

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“…One of them is the crustal magnetic field in the southern hemisphere of Mars that seems to affect the shape of the biggest and smaller layers in Mars's ionosphere (Nielsen et al, 2007). The effect of this magnetic field, as stated in a previous section, can be clearly observed in the left part of the ionograms, which suggests that the effect of the crustal magnetic field can be important at the spacecraft altitude (Zou et al, 2010).…”

Section: Discussionmentioning

confidence: 67%

Retrieval of ionospheric profiles from the Mars Express MARSIS experiment data and comparison with radio occultation data

Sánchez–Cano

Witasse

Herráiz

et al. 2012

Geosci. Instrum. Method. Data Syst.

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Abstract. Since 2005 the Mars Advanced Radar and Ionospheric Sounding experiment (MARSIS) aboard Mars Express has acquired a unique dataset on the ionosphere of Mars made up of ionospheric soundings taken by the instrument working in its active ionospheric sounding (AIS) mode. These soundings play a role similar to those of modern Terrestrial digisondes in the analysis of our planet ionosphere and have allowed us to dramatically improve our knowledge about the Martian ionosphere. This paper describes this kind of data, which are available from the public Planetary Science Archive, and introduces the MAISDAT tool developed by the European Space Agency to analyze and derive the vertical profile of electron density. Comparisons with radio occultation profiles obtained from Mars Express Radio Science instrument are performed to validate the procedure used in this study.

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“…Previous studies have demonstrated that perpendicular heating is an important aspect of particle dynamics of the crustal magnetic field cusps (Nielsen et al, 2007;Zou et al, 2010;Ulus ßen et al, 2011) and auroral regions at Mars (Lundin et al, 2006a,b;Dubinin et al, 2009), and may be the combination of heating from impacting precipitating electrons/solar wind particles, wave-particle interactions and magnetic mirroring effects. The evidence presented in this paper adds further support to wave-particle interactions as an important feature of open crustal magnetic fields on the dayside of Mars.…”

Section: Summary and Discussionmentioning

confidence: 99%

Properties of a large-scale flux rope and current sheet region on the dayside of Mars: MGS MAG/ER and MEX ASPERA-3 ELS observations

Soobiah

Wild

Beharrell

et al. 2014

Icarus

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a b s t r a c tWe present dual spacecraft observations by MGS MAG/ER and MEX ASPERA-3 ELS of a large-scale magnetic flux rope on the dayside of Mars that occurs in close proximity to the crustal magnetic fields and a dayside current sheet region. A current sheet (including the large-scale flux rope) was observed on repeated MGS orbits when the draped solar wind magnetic field present in the ionosphere had a þB y component (in MSO). Minimum Variance Analysis (MVA) of the large-scale flux rope and two current sheet crossings that occur after show a common peak in magnetic field along the intermediate variance direction, indicating the normal component of a reconnecting current sheet. All repeated orbits demonstrated evidence of a plasma boundary by the decrease in electron differential flux above 100 eV when moving into regions dominated by the crustal magnetic field, and coincided with the measured magnetic field strength being double the undisturbed crustal magnetic field. We argue this forms evidence of magnetic reconnection between crustal magnetic fields and draped solar wind magnetic field (from ionosphere or magnetosheath) at a ''mini-magnetopause'' type boundary on the dayside of Mars. Similar electron pitch angle distributions observed during the large-scale flux rope, current sheet crossings, and regions of radial crustal magnetic field, suggest these regions share a common magnetic field topology for the trapping of magnetosheath particles on open crustal magnetic fields on the dayside of Mars. As such, indicates a trapping quadrupole magnetic field exist either at the magnetic reconnection X-line region or where open crustal magnetic fields meet oppositely directed solar wind magnetic field. At a time when the draped solar wind magnetic field present in the ionosphere was weaker in strength, the current sheet crossing was observed over an extended region of 2000 km. The extended current sheet demonstrated properties of a hot diamagnetic region and features of a mirror mode structure or magnetic hole, the first time such a structure has been found in the ionosphere of Mars. Observations suggests lower energy electrons could be accelerated by a local process of perpendicular heating/pitch angle diffusion and supports similar results at the Earth's polar cusp reported by Nykyri et al. (Nykyri et al. [2012]. J. Atmos. Sol-Terr. Phys. 87, 70). Such large scale and energetic structures are usually associated with regions beyond a planet's ionosphere, and the occurrence within the ionosphere of Mars may have an important impact on escape processes and the evolution of the martian atmosphere.

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Effects of Martian crustal magnetic field on its ionosphere

Cited by 8 publications

References 37 publications

Determination of seasonal variations in the Martian neutral atmosphere from observations of ionospheric peak height

Determination of seasonal variations in the Martian neutral atmosphere from observations of ionospheric peak height

Retrieval of ionospheric profiles from the Mars Express MARSIS experiment data and comparison with radio occultation data

Properties of a large-scale flux rope and current sheet region on the dayside of Mars: MGS MAG/ER and MEX ASPERA-3 ELS observations

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