Coalescence of Macroscopic Flux Ropes at the Subsolar Magnetopause: Magnetospheric Multiscale Observations

Zhou, Meng; Berchem, Guy; Walker, R. J.; El‐Alaoui, M.; Deng, Xiaohua; Cazzola, Emanuele; Lapenta, Giovanni; Goldstein, M. L.; Paterson, W. R.; Pang, Y.; Ergun, R. E.; Lavraud, B.; Liang, Haoming; Russell, C. T.; Strangeway, R. J.; Zhao, Cong; Giles, B. L.; Pollock, C. J.; Lindqvist, Per‐Arne; Marklund, Göran; Wilder, F. D.; Khotyaintsev, Yuri V.; Torbert, R. B.; Burch, J. L.

doi:10.1103/physrevlett.119.055101

Cited by 86 publications

(111 citation statements)

References 40 publications

(35 reference statements)

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“…Zhou et al () reported the presence of an ion jet reversal ( v iz, GSM = ± 200 km/s; Figure c) during a magnetopause crossing (17 November 2015—02:13:40–02:14:40 UT) corresponding to a “dissipative” interaction of two neighboring FTEs. Shortly after this crossing, at the peak of the southward ion velocity, a chain of small‐scale FTEs is observed, labeled as “FTE 1” and “FTE 2.” In particular, two FTEs centered at 02:20:48 UT and 02:21:24 UT are observed surrounded by two southward v iz peaks (02:17:30 UT and 02:22 UT) which met our selection criteria (Akhavan‐Tafti et al, ).…”

Section: Analysis and Resultsmentioning

confidence: 98%

MMS Multi‐Point Analysis of FTE Evolution: Physical Characteristics and Dynamics

et al. 2019

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Previous studies have indicated that flux transfer events (FTEs) grow as they convect away from the reconnection site along the magnetopause. This increase in FTE diameter may occur via adiabatic expansion in response to decreasing external pressure away from the subsolar region or due to a continuous supply of magnetic flux and plasma to the FTEs' outer layers by magnetic reconnection. Here we investigate an ensemble of 55 FTEs at the subsolar magnetopause using Magnetospheric Multiscale (MMS) multi‐point measurements. The FTEs are initially modeled as quasi‐force‐free flux ropes in order to infer their geometry and the spacecraft trajectory relative to their central axis. The MMS observations reveal a radially‐inward net force at the outer layers of FTEs which can accelerate plasmas and fields toward the FTE's core region. Inside the FTEs, near the central axis, plasma density is found to decrease as the axial net force increases. It is interpreted that the axial net force accelerates plasmas along the axis in the region of compressing field lines. Statistical analysis of the MMS observations of the 55 FTEs indicates that plasma pressure, Pth, decreases with increasing FTE diameter, λ, as Pth,obsv ∝ λ−0.24. Assuming that all 55 FTEs started out with similar diameters, this rate of plasma pressure decrease with increasing FTE diameter is at least an order of magnitude slower than the theoretical rate for adiabatic expansion (i.e., Pth,adiab. ∝ λ−3.3), suggesting the presence of efficient plasma heating mechanisms, such as magnetic reconnection, to facilitate FTE growth.

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Section: Analysis and Resultsmentioning

confidence: 98%

MMS Multi‐Point Analysis of FTE Evolution: Physical Characteristics and Dynamics

et al. 2019

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“…The clear peaks of curl of E′ suggests that the electrons were not frozen-in to the magnetic field within this region (Goldman et al, 2016;Zhou et al, 2017). It has been reported that large guide field can magnetize electrons within the EDR (Eriksson et al, 2016;Zhou et al, 2017). It has been reported that large guide field can magnetize electrons within the EDR (Eriksson et al, 2016;Zhou et al, 2017).…”

Section: An Active X Line In the Exhaustmentioning

confidence: 92%

“…The thickness of this energy dissipation layer along N was 54 km/s * 0.33 s ≈ 18 km ≈ 12 d e . The clear peaks of curl of E′ suggests that the electrons were not frozen-in to the magnetic field within this region (Goldman et al, 2016;Zhou et al, 2017). The clear peaks of curl of E′ suggests that the electrons were not frozen-in to the magnetic field within this region (Goldman et al, 2016;Zhou et al, 2017).…”

Section: An Active X Line In the Exhaustmentioning

confidence: 96%

Observations of a Kinetic‐Scale Magnetic Hole in a Reconnection Diffusion Region

Zhong

Zhou

Huang

et al. 2019

Geophysical Research Letters

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Magnetic holes have been widely observed in various space plasma systems. The origin of magnetic holes and their influence to background plasma are under debate. In this paper, we show a kinetic‐scale electron vortex magnetic hole in a nonideal region of an active X line, which was observed by the Magnetospheric Multiscale mission at the dayside magnetopause. Intense current and nonideal electric field in the electron frame were observed within the magnetic hole, which led to a strong energy dissipation. Thus, the electron vortex magnetic hole probably provided an additional energy dissipation channel besides the electron diffusion region adjacent to the hole. We suggest that magnetic reconnection provided favorable conditions for the formation of this kinetic‐scale magnetic hole and is an important source of magnetic holes in space plasma.

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“…On the other hand, recent simulations and observations confirm that electron Kelvin‐Helmholtz instability can generate secondary MFR by forming electron vortex (Fermo et al, ; Huang, Lu, et al, ; Zhong et al, ). MFRs can coalesce to form larger MFRs, during which energy is dissipated and particles are energized (Wang et al, ; Zhou, Pang, et al, ; Zhou et al, ). Magnetic cloud in the solar wind, the prototype of which is MFR, may reconnect with the solar wind magnetic field around it and erode its magnetic flux (Ruffenach et al, ).…”

Section: Introductionmentioning

confidence: 99%

In Situ Observation of Magnetic Reconnection Between an Earthward Propagating Flux Rope and the Geomagnetic Field

Man

Zhou

Deng

et al. 2018

Geophysical Research Letters

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It has been proposed that, in the near‐Earth magnetotail, earthward propagating flux ropes can merge with the Earth's dipole magnetic field and dissipate its magnetic energy. However, the reconnection diffusion region related to this process has not been identified. Here we report the first in situ observation of magnetic reconnection between an earthward propagating flux rope and the closed magnetic field lines connecting to Earth. Magnetospheric Multiscale (MMS) spacecraft crossed a vertical current sheet between the leading edge of the flux rope (negative Bz) and the geomagnetic field (positive Bz). The subion‐scale current sheet, super‐Alfvénic electron outflow, Hall magnetic and electric field, conversion of magnetic energy to plasma energy (J·E > 0), and magnetic null were observed during the crossing. All the above signatures indicate that MMS detected the reconnection diffusion region. This result is also relevant to other planets with intrinsic magnetosphere.

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Coalescence of Macroscopic Flux Ropes at the Subsolar Magnetopause: Magnetospheric Multiscale Observations

Cited by 86 publications

References 40 publications

MMS Multi‐Point Analysis of FTE Evolution: Physical Characteristics and Dynamics

MMS Multi‐Point Analysis of FTE Evolution: Physical Characteristics and Dynamics

Observations of a Kinetic‐Scale Magnetic Hole in a Reconnection Diffusion Region

In Situ Observation of Magnetic Reconnection Between an Earthward Propagating Flux Rope and the Geomagnetic Field

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