Simultaneously Formed Wedge‐Like Structures of Different Ion Species Deep in the Inner Magnetosphere

Ren, Jie; Zong, Qiugang; Yue, Chao; Zhou, X.‐Z.; Fu, S. Y.; Funsten, H. O.

doi:10.1029/2020ja028192

Cited by 8 publications

(21 citation statements)

References 166 publications

(254 reference statements)

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“…In this paper, we revisit the Van Allen Probes A and B observations of wedge‐like ion spectral structures previously reported in Ren et al (2020). The observations, also shown in Figures 1 and 2, suggest that the inner edge of the structure appears at L ∼ 3 within a specific energy range of several keV.…”

Section: Summary and Discussionmentioning

confidence: 65%

“…However, their drift speeds are very low (mostly below 1 km/s, especially for the ions with

μ = 12

eV/nT; see the blue drift paths in Figure 3b), and the ion locations change very slightly in the next 7 hr (from the time of convection reduction to the observation time of the wedge‐like structures; see the minor difference between the distributions of the circles and the solid dots in Figure 3b and 3d). In other words, the wedge‐like structures deform very slowly after the reduction of magnetospheric convection, which provides a large time window for their observations in the nightside inner magnetosphere (Ren et al, 2020).…”

Section: Simulation and Interpretationsmentioning

confidence: 99%

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On the Formation of Wedge‐Like Ion Spectral Structures in the Nightside Inner Magnetosphere

et al. 2020

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Recent observations in the nightside inner magnetosphere have identified a series of wedge-like spectral structures in the energy-time spectrograms of oxygen, helium, and hydrogen ion fluxes. Although the shapes and distributions of these structures have been characterized by case and statistical studies, their formation mechanism remains unclear. Here we utilize a particle tracing model to reproduce the wedge-like structures successively observed by the twin Van Allen Probes. The model suggests that these structures originate from intermittent substorm injection, and it is the accessibility region of these injected ions that determines their shapes. This mechanism is similar to the formation of another kind of structures, the inner magnetospheric nose-like structures, except that the wedge-like structures are separated from the tail population by the discontinuation of ion injections. This scenario is also supported by the distribution statistics of wedge-like structures, which provides new insights into the dynamics of the magnetotail-inner magnetosphere coupled system. Plain Language Summary In Earth's inner magnetosphere, multiple plasma populations interact with one another to render a highly coupled system, with its dynamic evolution also subject to magnetospheric convection and magnetotail particle injections. The interplay of these complicated processes is manifested in spacecraft observations by various spectral structures of particle fluxes, and the understanding of their generation provides unique insights into the underlying processes. Here we focus on a specific type of spectral structures in the nightside inner magnetosphere, named the wedge-like structures. These structures are characterized by enhanced fluxes of oxygen, helium, and hydrogen ions at increasing energies (from a few eV to several keV) with decreasing equatorial distance to the Earth. Based on a particle tracing model, we successfully reproduce the structure characteristics observed by NASA's (National Aeronautics and Space Administration) twin Van Allen Probes. The model suggests that these structures originate from transient injections associated with substorm activities, and their shapes are determined by the energy-dependent ion accessibility into the inner magnetosphere. This scenario of wedge-like structure formation is consistent with both case and statistical results, which sheds new light on our current understanding of the inner magnetospheric dynamics and its coupling process with the magnetotail plasma sheet.

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Section: Summary and Discussionmentioning

confidence: 65%

“…However, their drift speeds are very low (mostly below 1 km/s, especially for the ions with

μ = 12

Section: Simulation and Interpretationsmentioning

confidence: 99%

On the Formation of Wedge‐Like Ion Spectral Structures in the Nightside Inner Magnetosphere

et al. 2020

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“…Ren et al. (2020) also found that these structures depended on substorm activities, and suggested that the source of wedge‐like structures was probably the nightside substorm injection. The wedge‐like structures reported in Ren et al.…”

Section: Introductionmentioning

confidence: 96%

“…In the inner magnetosphere, many spacecraft have detected a variety of ion spectral structures, which are named after the shapes of the energy bands or gaps for ion fluxes in the energy‐time (or energy‐ L shell) spectrograms. These structures include the nose‐like structures (e.g., Ferradas et al., 2016; Smith & Hoffman, 1974), the wedge‐like structures (Ren et al., 2020; Zhou et al., 2020), the finger‐like structures (Denton et al., 2016; Wang et al., 2020), the trunk‐like structures (Zhang et al., 2015), and the ion spectral gaps (e.g., Kovrazhkin et al., 1999; Shirai et al., 1997; Yue et al., 2021). Among these ion spectral structures, the nose‐like structures were first reported in the 1970s (Smith & Hoffman, 1974) and since then have been most extensively investigated via both spacecraft observations and simulations (Ebihara et al., 2004; Ejiri et al., 1980; Ferradas et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

The Link Between Wedge‐Like and Nose‐Like Ion Spectral Structures in the Inner Magnetosphere

Ren

Zhou

Zong

et al. 2021

Geophysical Research Letters

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The wedge‐like and nose‐like ion spectral structures, named after their characteristic shapes in the energy‐time spectrograms, appear to be distinctively different structures in the Earth's inner magnetosphere. Here. we present a case study with conjugate observations from the Arase spacecraft and the twin Van Allen Probes on July 1 and 2, 2017, which displayed the characteristic signatures of the wedge‐like and nose‐like ion structures, respectively. When the spacecraft nearly intersected at L = 2.8, the two structures overlapped with enhanced ion fluxes in the energy range of 1–10 keV. These observations suggest that the wedge‐like and nose‐like spectral signatures are merely the manifestations of one single structure along different spacecraft trajectories. This finding is further validated by the reproduction of both structures from a particle‐tracing model, which also indicates their formation processes associated with the intermittent substorm injections in the nightside magnetosphere.

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“…Several spacecraft missions in the inner magnetosphere have indeed detected various features in ion energy‐time spectrograms, which are named after the characteristic shapes of energy bands or gaps of ion fluxes. These spectral features include the “nose‐like” structures (e.g., Buzulukova, Kovrazhkin, et al., 2003; Ebihara, Ejiri, et al., 2004; Fennell et al., 1998; Ferradas et al., 2016a, 2016b; Ganushkina et al., 2001; Li et al., 2000; Smith & Hoffman, 1974; Vallat et al., 2007), the “wedge‐like” dispersions (e.g., Ebihara, Yamauchi, et al., 2001; Ren et al., 2020; Zhou et al., 2020), the “trunk‐like” structures (Zhang et al., 2015), and ion spectral gaps (e.g., Buzulukova, Galperin, et al., 2002; Fennell et al., 1981; Kaye et al., 1981; Kistler et al., 1989; Kistler & Mouikis, 2016; Kovrazhkin et al., 1999; Lennartsson et al., 1979; Shirai et al., 1997). As expected, statistical studies of ion spectral features have reported their dependence on geomagnetic conditions.…”

Section: Introductionmentioning

confidence: 99%

Sustained Oxygen Spectral Gaps and Their Dynamic Evolution in the Inner Magnetosphere

et al. 2021

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Simultaneously Formed Wedge‐Like Structures of Different Ion Species Deep in the Inner Magnetosphere

Cited by 8 publications

References 166 publications

On the Formation of Wedge‐Like Ion Spectral Structures in the Nightside Inner Magnetosphere

On the Formation of Wedge‐Like Ion Spectral Structures in the Nightside Inner Magnetosphere

The Link Between Wedge‐Like and Nose‐Like Ion Spectral Structures in the Inner Magnetosphere

Sustained Oxygen Spectral Gaps and Their Dynamic Evolution in the Inner Magnetosphere

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