The Magnetospheric Driving Source of Double‐Peak Subauroral Ion Drifts: Double Ring Current Pressure Peaks

Wei, Dong; Yu, Yiqun; He, Fei

doi:10.1029/2019gl083186

Cited by 14 publications

(27 citation statements)

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“…Although a number of SAPS simulation studies have reproduced basic properties of SAPS (e.g., Ferdousi et al, 2019; Yu et al, 2015), it has been challenging to simulate SAID due to difficulties in accurately specifying localized magnetospheric drivers. Particle injection has been considered to initiate SAID (Buzulukova et al, 2010; Wei et al, 2019; Zhang et al, 2009). However, it is not understood what nature of particle injection distinguishes SAPS and SAID.…”

Section: Introductionmentioning

confidence: 99%

Magnetospheric Conditions for STEVE and SAID: Particle Injection, Substorm Surge, and Field‐Aligned Currents

et al. 2020

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To understand magnetosphere‐ionosphere conditions that result in thermal emission velocity enhancement (STEVE) and subauroral ion drifts (SAID) during the substorm recovery phase, we present substorm aurora, particle injection, and current systems during two STEVE events. Those events are compared to substorm events with similar strength but without STEVE. We found that the substorm surge and intense upward currents for the events with STEVE reach the dusk, while those for the non‐STEVE substorms are localized around midnight. The Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite observations show that location of particle injection and fast plasma sheet flows for the STEVE events also shifts duskward. Electron injection is stronger and ion injection is weaker for the STEVE events compared to the non‐STEVE events. SAID are measured by Super Dual Auroral Radar Network during the STEVE events, but the non‐STEVE events only showed latitudinally wide subauroral polarization streams without SAID. To interpret the observations, Rice Convection Model (RCM) simulations with injection at premidnight and midnight have been conducted. The simulations successfully explain the stronger electron injection, weaker ion injection, and formation of SAID for injection at premidnight, because injected electrons reach the premidnight inner magnetosphere and form a narrower separation between the ion and electron inner boundaries. We suggest that substorms and particle injections extending far duskward away from midnight offer a condition for creating STEVE and SAID due to stronger electron injection to premidnight. The THEMIS all‐sky imager network identified the east‐west length of the STEVE arc to be ~1900 km (~2.5 h magnetic local time) and the duration to be 1–1.5 h.

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Section: Introductionmentioning

confidence: 99%

Magnetospheric Conditions for STEVE and SAID: Particle Injection, Substorm Surge, and Field‐Aligned Currents

et al. 2020

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“…In Figure 5d, the differential electron/ion flux time series illustrate dispersionless particle injections and flux increases (EF at 50-225 keV and 315-1,500 keV; PF at 50-400 keV and 1.2-5.0 MeV; shaded interval in yellow) just before the DSAID-ASAID detection (dot in green). Meanwhile, the 225 keV proton density line plot illustrates a double proton density peak feature (shaded interval in light orange) occurring just before the DSAID-ASAID detection and thus provides observational evidence of the formation of a double RC plasma density/ pressure peak structure that led to the development of two sets of ↓R2 FACs (Wei et al, 2019) and of this DSAID-ASAID feature's DSAID component (dot in green). Later on, a smaller and highly asymmetric double peak structure developed leading to two uneven sets of ↓R2 FACs and thus, to the development of this highly asymmetric DSAID feature (dot in orange; shaded interval in light cyan).…”

Section: Dsaid-asaid Declining To Dsaidmentioning

confidence: 89%

“…These increasing ↓R2 FACs connected with ↑R1 FACs via poleward directed Pedersen currents (J P ) at the equatorward edge of the auroral zone. At the poleward edge of the auroral zone, the HR (shaded interval in gray) was still present implying enhanced ↑R1 FACs (see the steep ΔB Y gradient) and the SCW2L system's operation when a double RC plasma density/pressure peak structure developed (as detected by LANL, see Figure 5d and details in Section 3.3.4) leading to DSAID development (Wei et al, 2019; see also details in Section 3.2.3) showing the characteristics of SAPS development (He et al, 2016). Figure 5c illustrates the orbit of LANL L7 on November 8, 2004.…”

Section: Dsaid-asaid Declining To Dsaidmentioning

confidence: 99%

“…More recent investigations of Wei et al (2019) applied the short-circuiting theory (Mishin & Puhl-Quinn, 2007; see details above) to DSAID development. Wei et al (2019) demonstrated with Van Allen Probe B measurements that the previ-ous repeating RC injections intensified the partial RC and thus created a double pressure peak structure in the near-Earth dusk-midnight MLT sector leading to two sets of ↓R2 FACs in the ionospheric sub-auroral region-showing the characteristics of SAPS development (He et al, 2016)-and to DSAID development.…”

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confidence: 99%

“…Same asFigure 2but for the earlier northern-hemisphere DSAID-ASAID detected on January 21, 2005. ASAID, abnormal sub-auroral ion drifts; DSAID, double-peak sub-auroral ion drifts (Wei et al, 2019),. (ii) generating large poleward E fields in the meridional Pedersen currents, and thus (iii) leading to DSAID development showing the characteristics of SAPS development(He et al, 2016) as detected by DMSP (see…”

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confidence: 99%

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Complex Sub‐Auroral Flow Channel Structure Formed by Double‐Peak Sub‐Auroral Ion Drifts (DSAID) and Abnormal Sub‐Auroral Ion Drifts (ASAID)

Horvath

Lovell

2020

JGR Space Physics

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By utilizing multi‐instrument and multi‐satellite/spacecraft observations, we report the repeated development of a temporary and complex sub‐auroral flow channel (FC) structure during the intensive storms investigated. Appearing as combined double‐peak sub‐auroral ion drifts (DSAID) and abnormal SAID (ASAID), it is called DSAID‐ASAID FC structure. Revealing its development, various other FCs and features appeared in the auroral and polar regions simultaneously. These include the auroral Harang Region (HR) that is the Substorm Current Wedge's ionospheric signature and the Eastward FC (E‐FC) indicating the arrival of the Westward Travelling Surge. Results show that in the HR and E‐FC, the locally enhanced duskside upward Region 1 Field Aligned Currents (↑R1 FACs) connected in the magnetosphere with the meridional partial ring current characterized by a double plasma density/pressure peak structure, of which signature was seen in the 225 keV proton density data, leading to the development of two sets of ↓R2 FACs and DSAID. Meanwhile, large auroral undulations appeared and were driven, via magnetosphere‐ionosphere coupling, by Kelvin‐Helmholtz instability mechanisms that also drove plasma sheet rippling leading to ASAID development. Plasma sheet rippling occurred during magnetotail reconnection, as demonstrated with its ionospheric polar cap signature, known as FC‐3, in a stretched tail region according to the b2i boundary located at ∼60° magnetic latitude. Then, the earthward flows' braking/slowing down provided the energy for driving the R1‐R2 FACs. From the observational evidence presented we conclude that the DSAID‐ASAID features investigated developed due to the maintenance of DSAID during plasma sheet rippling triggering ASAID development.

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Meso-Scale Electrodynamic Coupling of the Earth Magnetosphere-Ionosphere System

Cao

et al. 2022

Space Sci Rev

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Within the fully integrated magnetosphere-ionosphere system, many electrodynamic processes interact with each other. We review recent advances in understanding three major meso-scale coupling processes within the system: the transient field-aligned currents (FACs), mid-latitude plasma convection, and auroral particle precipitation. (1) Transient FACs arise due to disturbances from either dayside or nightside magnetosphere. As the interplanetary shocks suddenly compress the dayside magnetosphere, short-lived FACs are induced at high latitudes with their polarity successively changing. Magnetotail dynamics, such as substorm injections, can also disturb the current structures, leading to the formation of substorm current wedges and ring current disruption. (2) The mid-latitude plasma convection is closely associated with electric fields in the system. Recent studies have unraveled some important features and mechanisms of subauroral fast flows. (3) Charged particles, while drifting around the Earth, often experience precipitating loss down to the upper atmosphere, enhancing the auroral conductivity. Recent studies have been devoted to developing more self-consistent geospace circulation models by including a better representation of the auroral conductance. It is expected that including these new advances in geospace circulation models could promisingly strengthen their forecasting capability in space weather applications. The remaining challenges especially in the global modeling of the circulation system are also discussed.

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The Magnetospheric Driving Source of Double‐Peak Subauroral Ion Drifts: Double Ring Current Pressure Peaks

Cited by 14 publications

References 50 publications

Magnetospheric Conditions for STEVE and SAID: Particle Injection, Substorm Surge, and Field‐Aligned Currents

Magnetospheric Conditions for STEVE and SAID: Particle Injection, Substorm Surge, and Field‐Aligned Currents

Complex Sub‐Auroral Flow Channel Structure Formed by Double‐Peak Sub‐Auroral Ion Drifts (DSAID) and Abnormal Sub‐Auroral Ion Drifts (ASAID)

Meso-Scale Electrodynamic Coupling of the Earth Magnetosphere-Ionosphere System

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