Auroral Arcs and Ion Outflow

Maggiolo, Romain

doi:10.1002/9781118978719.ch4

Cited by 5 publications

(5 citation statements)

References 140 publications

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“…There are two main regions where energetic (>100 eV) O + outflow is observed: the cusp and the nightside aurora. The processes leading to this ion outflow and the outflow characteristics have been recently reviewed by Maggiolo (2016). Ions are accelerated from both regions by a two-step process.…”

Section: Introductionmentioning

confidence: 99%

Cusp and Nightside Auroral Sources of O⁺ in the Plasma Sheet

et al. 2019

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Energetic O + outflow is observed from both the dayside cusp and the nightside aurora, but the relative importance of these regions in populating the plasma sheet and ring current is not known. During a storm on 16 July 2017, the Arase and MMS satellites were located in the near-earth and midtail plasma sheet boundary layers (PSBL). During the storm main phase, Arase and MMS both observe O + in the lobe entering the PSBL, followed by a time period with energy-dispersed bursts of tailward-streaming O + . The ions at MMS are at higher energies than at Arase. Trajectory modeling shows that the ions coming in from the lobe are cusp origin, while the more energetic bursty ions are from the nightside aurora. The observed and simulated energies and temporal dispersion are consistent with these sources. Thus, both regions directly contribute O + to the plasma sheet during this storm main phase. Plain Language SummaryThe magnetosphere is the region of space encompassed by Earth's magnetic field. The plasma trapped in the magnetosphere can come both from the Sun and from the ionosphere, the ionized layer of the atmosphere. The ionospheric contribution to the plasma increases during geomagnetic storms. These ions get energized in the auroral oval and flow out along magnetic field lines. During storms, this outflow can contain a large fraction of O + . There are two particular regions where this O + outflow occurs, one on the dayside and one on the nightside. This study looks at the contribution of O + from these two regions. Two spacecraft in different locations in the magnetosphere during the storm were able to observe the signatures of ions from both regions indicating that both regions are important during the peak of the storm.

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Section: Introductionmentioning

confidence: 99%

Cusp and Nightside Auroral Sources of O⁺ in the Plasma Sheet

et al. 2019

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“…Previous studies did not suggest that larger Poynting fluxes into the ionosphere can also result in higher temperatures for the outflow ions. Since the DMSP observation indicates the existence of upward FACs and upward field‐aligned potential around the footprints of TH‐D and TH‐E (Figure 7), here we consider that the upward field‐aligned potential associated with upward FACs can increase the temperatures of outflow ions (e.g., Maggiolo, 2015). The field‐aligned potential is typically located below 2 R E .…”

Section: Discussion Of Possible Processes For the Enhancement And Ene...mentioning

confidence: 99%

“…These transport and energization processes have been investigated with test‐particle tracing simulations and can account for the main features of the statistical occurrence probabilities of the warm field‐aligned ions (Chappel et al., 2008). In addition, non‐adiabatic processes along the field lines connecting the auroral zone and plasma sheet, such as interaction with dispersive Alfvén waves (e.g., Chaston et al., 2015) and acceleration by field‐aligned potential (e.g., Maggiolo, 2015), can also contribute to the energization in the field‐aligned direction.…”

Section: Introductionmentioning

confidence: 99%

Energy‐Dispersive Field‐Aligned Warm Ion Enhancement in the Plasma Sheet During a Substorm Growth Phase: A THEMIS Event

Wang

Wing

et al. 2023

JGR Space Physics

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The solar wind and the ionosphere are the two particle sources for the Earth's magnetosphere. In the near-Earth magnetosphere, observations have shown that ions upflowing from the ionosphere, mainly H + , He + , and O + ions, can form cold (<∼10 eV) ions inside the plasmapause and warm (∼10-1,000 eV) field-aligned ions outside the plasmapause (e.g., Chappell et al., 2008). These two ion populations of the ionospheric source are distinguished from the hot (from ∼1 keV to 10's keV) isotropic plasma sheet ions and energetic (>∼20 keV) ring current ions that are a mixture of the solar wind and ionosphere sources. Their differences in the energy ranges and pitch-angle distribution types are a result of different transport, energization, and pitch-angle scattering processes.

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“…These ions can originate from the dayside cusp or the nightside auroral region (e.g., Kronberg et al., 2014). The initial acceleration that leads to escape can occur through several different mechanisms that take place at different altitudes in the ionosphere (Maggiolo, 2015). Due to the magnetospheric configuration, outflowing ions originated at the dayside cusp have been observed to travel along field lines that are convecting toward the nightside, and they reach the plasma sheet at different radial locations with different energies, due to a velocity filter effect (Kistler et al., 2019).…”

Section: Introductionmentioning

confidence: 99%

Temporal Evolution of O⁺ Population in the Near‐Earth Plasma Sheet During Geomagnetic Storms as Observed by the Magnetospheric Multiscale Mission

Regoli,

Gkioulidou,

Ohtani

et al. 2024

JGR Space Physics

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During geomagnetic storms, the increase in energy input into the ionosphere in the form of Poynting flux and electron precipitation leads to an enhanced ionospheric outflow that results in an increase of the O+ content in the magnetosphere. Using different missions and instrumentation, two main ionospheric sources have been identified for the oxygen ions reaching the inner magnetosphere during geomagnetic storms: the dayside cusp, and the night side auroral region. Evidence of both pathways have been presented in the literature. However, the relative contribution of each of these pathways to the enhancement of O+ observed in near‐Earth plasma sheet, as well as the dynamics involved during the development of geomagnetic storms remains an open question. Here, we present the first statistical study to date to address this question, in the form of a superposed epoch analysis of O+ and H+ moments obtained by the Magnetospheric Multiscale (MMS) mission throughout the main phase of 90 geomagnetic storms with a minimum SYM‐H of at least −50 nT. The results show a clear increase in the oxygen density in the near‐Earth plasma sheet, with values further from Earth remaining low. Temperature values for both species show an increase with the progress of the storms. These results combined suggest that, during the main phase of geomagnetic storms, most of the oxygen ions observed in the near‐Earth plasma sheet are traveling directly from the nightside auroral region.

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Auroral Arcs and Ion Outflow

Cited by 5 publications

References 140 publications

Cusp and Nightside Auroral Sources of O⁺ in the Plasma Sheet

Cusp and Nightside Auroral Sources of O⁺ in the Plasma Sheet

Energy‐Dispersive Field‐Aligned Warm Ion Enhancement in the Plasma Sheet During a Substorm Growth Phase: A THEMIS Event

Temporal Evolution of O⁺ Population in the Near‐Earth Plasma Sheet During Geomagnetic Storms as Observed by the Magnetospheric Multiscale Mission

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Auroral Arcs and Ion Outflow

Cited by 5 publications

References 140 publications

Cusp and Nightside Auroral Sources of O+ in the Plasma Sheet

Cusp and Nightside Auroral Sources of O+ in the Plasma Sheet

Energy‐Dispersive Field‐Aligned Warm Ion Enhancement in the Plasma Sheet During a Substorm Growth Phase: A THEMIS Event

Temporal Evolution of O+ Population in the Near‐Earth Plasma Sheet During Geomagnetic Storms as Observed by the Magnetospheric Multiscale Mission

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Cusp and Nightside Auroral Sources of O⁺ in the Plasma Sheet

Cusp and Nightside Auroral Sources of O⁺ in the Plasma Sheet

Temporal Evolution of O⁺ Population in the Near‐Earth Plasma Sheet During Geomagnetic Storms as Observed by the Magnetospheric Multiscale Mission