Stationary flux ropes at the southern terminator of Mars

Beharrell, M. J.; Wild, J. A.

doi:10.1029/2012ja017738

Cited by 24 publications

(45 citation statements)

References 20 publications

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“…Morgan et al (2011) presented dual spacecraft observations at the Mars terminator of a large-scale flux rope that was quasisteady between each spacecraft pass of 30 min. Beharrell and Wild (2012) showed these structures are also quasi-stationary over approximately 7 days or more when observed on successive orbits of the Mars Global Surveyor (MGS) spacecraft that repeat the same path in Mars planetocentric (MPC) and Mars Solar Orbital (MSO) reference frames. Brain et al (2010) proposed that observations of current sheets between the large-scale flux ropes and the upstream crustal magnetic field region, was indicative of magnetic reconnection and the detachment of the plasmoid, causing a bulk removal process of the ionosphere.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 97%

“…This analysis includes a comparison of the work initiated by Beharrell and Wild (2012) for MGS data with observations made by MEX. Beharrell and Wild (2012) searched for the magnetic signatures of flux ropes in MGS Magnetometer (MAG) data during the mapping phase of MGS from March, 1999to November, 2006 During mapping phase, MGS has a Sun-synchronous orbit near 2:00 am/2:00 pm, with an altitude ranging from 368 km to 438 km.…”

Section: Instrumentationmentioning

confidence: 99%

“…Beharrell and Wild (2012) searched for the magnetic signatures of flux ropes in MGS Magnetometer (MAG) data during the mapping phase of MGS from March, 1999to November, 2006 During mapping phase, MGS has a Sun-synchronous orbit near 2:00 am/2:00 pm, with an altitude ranging from 368 km to 438 km. The orbit of MGS also retraces its path in the Mars planetocentric frame (MPC) after 88 orbits (7 martian solar days), with a small offset to the east of 58.6 km when measured at the equator.…”

Section: Instrumentationmentioning

confidence: 99%

“…The large-scale flux ropes have primarily been studied at the terminator of Mars Morgan et al, 2011;Beharrell and Wild, 2012) and Venus (Zhang et al, 2012b), where there is a greater occurrence (Beharrell and Wild, 2012). Large-scale flux ropes that occur near the terminator of Mars have been identified downstream from the strong martian crustal magnetic fields in the southern hemisphere, suggesting regions of closed crustal magnetic field are stretched downstream by the solar wind flow forming a plasmoid-like structure Morgan et al, 2011;Beharrell and Wild, 2012). Morgan et al (2011) presented dual spacecraft observations at the Mars terminator of a large-scale flux rope that was quasisteady between each spacecraft pass of 30 min.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

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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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Section: Contents Lists Available At Sciencedirectmentioning

confidence: 97%

Section: Instrumentationmentioning

confidence: 99%

Section: Instrumentationmentioning

confidence: 99%

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

See 2 more Smart Citations

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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“…The mapping orbit of MGS means that it returns to approximately the same location over the surface every 88 orbits (~7 Mars days). Beharrell and Wild [2012] examined the context of the 9 March 2002 flux rope by analyzing the magnetic field observed by MGS in the weeks before and after when similar viewing geometries were encountered. They found that flux rope signatures were also observed at these times, although the 9 March signature was by far the strongest.…”

Section: Flux Ropes Associated With Crustal Fieldsmentioning

confidence: 99%

Origin and Evolution of Plasmoids and Flux Ropes in the Magnetotails of Earth and Mars

Eastwood

Kiehas

2015

Magnetotails in the Solar System

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The spatial structure of Martian magnetic flux ropes recovered by the Grad‐Shafranov reconstruction technique

et al. 2014

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We applied the Grad-Shafranov (GS) reconstruction technique to Martian magnetic flux ropes observed by Mars Global Surveyor in order to estimate their spatial structures. This technique can provide a magnetic field map of their cross section from single spacecraft data, under the assumption that the structure is two-dimensional, magnetohydrostatic, and time independent. We succeeded in recovering the spatial structure for 70 events observed between April 1999 and November 2006. The reconstruction results indicate that the flux rope axes were mostly oriented horizontal to the Martian surface and were randomly distributed with respect to the typical plasma streamline. A subset of events with duration longer than 240 s was observed at solar zenith angles larger than 75• . These events all occur downstream from strong crustal magnetic field in the southern hemisphere, indicating an association between the crustal fields and the detected flux ropes. Using the shape and size of the flux ropes obtained from the GS reconstruction, we estimate lower limits on their volume that span 2-3 orders of magnitude, with larger flux ropes observed downstream from strong crustal magnetic fields. Estimated ion escape rates associated with flux ropes are of the order of 10 22 -10 23 ion/s, being approximately 10% of previously estimated escape rates during solar minimum.

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Stationary flux ropes at the southern terminator of Mars

Cited by 24 publications

References 20 publications

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

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

Origin and Evolution of Plasmoids and Flux Ropes in the Magnetotails of Earth and Mars

The spatial structure of Martian magnetic flux ropes recovered by the Grad‐Shafranov reconstruction technique

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