MESSENGER observations of large dayside flux transfer events: Do they drive Mercury's substorm cycle?

Imber, Suzanne M.; Slavin, J. A.; Boardsen, S. A.; Anderson, B. J.; Korth, H.; McNutt, R. L.; Solomon, Sean C.

doi:10.1002/2014ja019884

Cited by 56 publications

(116 citation statements)

References 69 publications

(91 reference statements)

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“…These values are lower than previous estimates (e.g., DiBraccio, Slavin, Raines, et al, ; Imber et al, ). However, our study includes all MESSENGER observations and does not focus on large amplitude events (such as the large FTEs observed by Imber et al, and the large mantle dispersion observed by DiBraccio, Slavin, Raines, et al, ). Therefore, our study includes quiet magnetospheric conditions as well as the extreme events.…”

Section: Observationscontrasting

confidence: 71%

“…Large fluctuations in the magnetic field data can be seen at the magnetopause (the magnetopause is marked by the middle and right vertical dashed lines), as well as in the plasma sheet. These are largely due to the presence of flux ropes, with flux transfer events being observed at the magnetopause and plasmoids in the plasma sheet (e.g., DiBraccio, Slavin, Imber, et al, ; Imber et al, ; Slavin et al, ), as well as dipolarization fronts in the plasma sheet (Sun et al, ; Sundberg et al, ).…”

Section: Observationsmentioning

confidence: 99%

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Mercury's Solar Wind Interaction as Characterized by Magnetospheric Plasma Mantle Observations With MESSENGER

et al. 2017

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We analyze 94 traversals of Mercury's southern magnetospheric plasma mantle using data from the MESSENGER spacecraft. The mean and median proton number densities in the mantle are 1.5 and 1.3 cm−3, respectively. For sodium number density these values are 0.004 and 0.002 cm−3. Moderately higher densities are observed on the magnetospheric dusk side. The mantle supplies up to 1.5 × 108 cm−2 s−1 and 0.8 × 108 cm−2 s−1 of proton and sodium flux to the plasma sheet, respectively. We estimate the cross‐electric magnetospheric potential from each observation and find a mean of ~19 kV (standard deviation of 16 kV) and a median of ~13 kV. This is an important result as it is lower than previous estimations and shows that Mercury's magnetosphere is at times not as highly driven by the solar wind as previously thought. Our values are comparable to the estimations for the ice giant planets, Uranus and Neptune, but lower than Earth. The estimated potentials do have a very large range of values (1–74 kV), showing that Mercury's magnetosphere is highly dynamic. A correlation of the potential is found to the interplanetary magnetic field (IMF) magnitude, supporting evidence that dayside magnetic reconnection can occur at all shear angles at Mercury. But we also see that Mercury has an Earth‐like magnetospheric response, favoring −BZ IMF orientation. We find evidence that −BX orientations in the IMF favor the southern cusp and southern mantle. This is in agreement with telescopic observations of exospheric emission, but in disagreement with modeling.

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Section: Observationscontrasting

confidence: 71%

Section: Observationsmentioning

confidence: 99%

Mercury's Solar Wind Interaction as Characterized by Magnetospheric Plasma Mantle Observations With MESSENGER

et al. 2017

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“…These FTEs being swept into the magnetotail at a rate of 0.5 per second implies a mean contribution to Mercury's cross-magnetospheric potential drop is 16 kV. Further, this FTE flux transfer rate is comparable to that estimated for the non-FTE magnetic flux being transferred to the magnetotail (DiBraccio et al, 2013;Imber et al, 2014;Slavin et al, 2009). Further, this FTE flux transfer rate is comparable to that estimated for the non-FTE magnetic flux being transferred to the magnetotail (DiBraccio et al, 2013;Imber et al, 2014;Slavin et al, 2009).…”

Section: Ddm Flux Transfer Eventsmentioning

confidence: 56%

MESSENGER Observations of Disappearing Dayside Magnetosphere Events at Mercury

et al. 2019

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MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) measurements taken during passes over Mercury's dayside hemisphere indicate that on four occasions the spacecraft remained in the magnetosheath even though it reached altitudes below 300 km. During these disappearing dayside magnetosphere (DDM) events, the spacecraft did not encounter the magnetopause until it was at very high magnetic latitudes, ~66 to 80°. These DDM events stand out with respect to their extremely high solar wind dynamic pressures, Psw ~140 to 290 nPa, and intense southward magnetic fields, Bz ~ −100 to −400 nT, measured in the magnetosheath. In addition, the bow shock was observed very close to the surface during these events with a subsolar altitude of ~1,200 km. It is suggested that DDM events, which are closely associated with coronal mass ejections, are due to solar wind compression and/or reconnection‐driven erosion of the dayside magnetosphere. The very low altitude of the bow shock during these events strongly suggests that the solar wind impacts much of Mercury's sunlit hemisphere during these events. More study of these disappearing dayside events is required, but it is likely that solar wind sputtering of neutrals from the surface into the exosphere maximizes during these intervals.

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“…Mariner 10 and MESSENGER flyby data suggested strongly that substorm‐like events occur in Mercury's magnetosphere, but on a time scale much shorter, ~2–3 min, than at Earth [ Siscoe et al , ; Slavin et al , ]. Measurements from the MESSENGER spacecraft [ Slavin et al , , , ; DiBraccio et al , ; Imber et al , ] have demonstrated convincingly that strong magnetic reconnection occurs at Mercury between the incident interplanetary magnetic field and the dayside Mercury magnetic field. Reconnection events and flux transfer event signatures at the dayside magnetopause, as well as “plasmoids” and magnetic traveling compression regions on the nightside, clearly demonstrate and extend our understanding of the dynamic nature of Mercury's magnetosphere.…”

Section: Discussionmentioning

confidence: 99%

Intense energetic electron flux enhancements in Mercury's magnetosphere: An integrated view with high‐resolution observations from MESSENGER

et al. 2016

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The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury has provided a wealth of new data about energetic particle phenomena. With observations from MESSENGER's Energetic Particle Spectrometer, as well as data arising from energetic electrons recorded by the X‐Ray Spectrometer and Gamma‐Ray and Neutron Spectrometer (GRNS) instruments, recent work greatly extends our record of the acceleration, transport, and loss of energetic electrons at Mercury. The combined data sets include measurements from a few keV up to several hundred keV in electron kinetic energy and have permitted relatively good spatial and temporal resolution for many events. We focus here on the detailed nature of energetic electron bursts measured by the GRNS system, and we place these events in the context of solar wind and magnetospheric forcing at Mercury. Our examination of data at high temporal resolution (10 ms) during the period March 2013 through October 2014 supports strongly the view that energetic electrons are accelerated in the near‐tail region of Mercury's magnetosphere and are subsequently “injected” onto closed magnetic field lines on the planetary nightside. The electrons populate the plasma sheet and drift rapidly eastward toward the dawn and prenoon sectors, at times executing multiple complete drifts around the planet to form “quasi‐trapped” populations.

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MESSENGER observations of large dayside flux transfer events: Do they drive Mercury's substorm cycle?

Cited by 56 publications

References 69 publications

Mercury's Solar Wind Interaction as Characterized by Magnetospheric Plasma Mantle Observations With MESSENGER

Mercury's Solar Wind Interaction as Characterized by Magnetospheric Plasma Mantle Observations With MESSENGER

MESSENGER Observations of Disappearing Dayside Magnetosphere Events at Mercury

Intense energetic electron flux enhancements in Mercury's magnetosphere: An integrated view with high‐resolution observations from MESSENGER

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