Ion‐scale secondary flux ropes generated by magnetopause reconnection as resolved by MMS

Eastwood, J. P.; Phan, T. D.; Cassak, P. A.; Gershman, D. J.; Haggerty, Colby; Malakit, K.; Shay, M. A.; Mistry, R.; Øieroset, M.; Russell, C. T.; Slavin, J. A.; Argall, M. R.; Avanov, L. A.; Burch, J. L.; Chen, Li‐Jen; Dorelli, J.; Ergun, R. E.; Giles, B. L.; Khotyaintsev, Yuri V.; Lavraud, B.; Lindqvist, Per‐Arne; Moore, T. E.; Nakamura, R.; Paterson, W. R.; Pollock, C. J.; Strangeway, R. J.; Torbert, R. B.; Wang, S.

doi:10.1002/2016gl068747

Cited by 97 publications

(152 citation statements)

References 37 publications

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“…This is indeed what we observe when investigating statistically the angle between the axis obtained in Eastwood et al (2016) and the minimal MCA eigenvector direction around 13:04:34 UT (when the spacecraft was passing closest to the flux-rope core, as highlighted by the shading in the figure). In particular, one would expect e min to identify the axis direction of flux ropes (as explained in section 2).…”

Section: Characteristic Shapes and Dimensionalities Inside Flux Ropessupporting

confidence: 79%

“…While a first glance at the quantities in panels (a) to (d) might suggest that this event is similar to the previous one (note in particular similarities in the pressures), strong differences in the plasma properties before and after the magnetic field peak led Kacem et al (2018) Eastwood et al (2016) that identifies the two flux rope crossings highlighted by the shaded strips, labeled "FR 1" and "FR 2." Notice that the "least variance" direction given by ±e min is well aligned with the flux rope axis estimated by Eastwood et al (2016) Kacem et al (2018) and Zhou et al (2018), which both identified the shaded time interval labeled "CS" as a current sheet crossing. The four lower panels display MCA results: (e) eigenvalues, (f) shape parameters (E and P), and (g-h) the three components of the maximal and minimal normalized eigenvectors, respectively.…”

Section: Characteristic Shapes and Dimensionalities Inside Flux Ropesmentioning

confidence: 54%

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Four‐Spacecraft Measurements of the Shape and Dimensionality of Magnetic Structures in the Near‐Earth Plasma Environment

et al. 2019

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We present a new method for determining the main relevant features of the local magnetic field configuration, based entirely on the knowledge of the magnetic field gradient four‐spacecraft measurements. The method, named “magnetic configuration analysis” (MCA), estimates the spatial scales on which the magnetic field varies locally. While it directly derives from the well‐known magnetic directional derivative and magnetic rotational analysis procedures (Shi et al., 2005, htpps://doi.org/10.1029/2005GL022454; Shen et al., 2007, https://doi.org/10.1029/2005JA011584), MCA was specifically designed to address the actual magnetic field geometry. By applying MCA to multispacecraft data from the Magnetospheric Multiscale (MMS) satellites, we perform both case and statistical analyses of local magnetic field shape and dimensionality at very high cadence and small scales. We apply this technique to different near‐Earth environments and define a classification scheme for the type of configuration observed. While our case studies allow us to benchmark the method with those used in past works, our statistical analysis unveils the typical shape of magnetic configurations and their statistical distributions. We show that small‐scale magnetic configurations are generally elongated, displaying forms of cigar and blade shapes, but occasionally being planar in shape like thin pancakes (mostly inside current sheets). Magnetic configurations, however, rarely show isotropy in their magnetic variance. The planar nature of magnetic configurations and, most importantly, their scale lengths strongly depend on the plasma β parameter. Finally, the most invariant direction is statistically aligned with the electric current, reminiscent of the importance of electromagnetic forces in shaping the local magnetic configuration.

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Section: Characteristic Shapes and Dimensionalities Inside Flux Ropessupporting

confidence: 79%

Section: Characteristic Shapes and Dimensionalities Inside Flux Ropesmentioning

confidence: 54%

Four‐Spacecraft Measurements of the Shape and Dimensionality of Magnetic Structures in the Near‐Earth Plasma Environment

et al. 2019

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“…Observations of electrons that were not trapped within the core of the event, thus, demonstrated that the FTE was three-dimensional and had an open magnetic field topology rather than the structure of a two-dimensional magnetic island [Øieroset et al, 2011]. Eastwood et al [2016] reported ion-scale (~7 ion inertial length radius) FTEs and demagnetized ions observed by Magnetospheric Multiscale mission (MMS). Eastwood et al [2016] reported ion-scale (~7 ion inertial length radius) FTEs and demagnetized ions observed by Magnetospheric Multiscale mission (MMS).…”

Section: Introductionmentioning

confidence: 99%

The substructure of a flux transfer event observed by the MMS spacecraft

Hwang

Sibeck

Giles

et al. 2016

Geophysical Research Letters

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On 15 August 2015, MMS (Magnetospheric Multiscale mission), skimming the dusk magnetopause, detected an isolated region of an increased magnetic strength and bipolar Bn, indicating a flux transfer event (FTE). The four spacecraft in a tetrahedron allowed for investigations of the shape and motion of the FTE. In particular, high‐resolution particle data facilitated our exploration of FTE substructures and their magnetic connectivity inside and surrounding the FTE. Combined field and plasma observations suggest that the core fields are open, magnetically connected to the northern magnetosphere from which high‐energy particles leak; ion “D” distributions characterize the axis of flux ropes that carry old‐opened field lines; counterstreaming electrons superposed by parallel‐heated components populate the periphery surrounding the FTE; and the interface between the core and draped regions contains a separatrix of newly opened magnetic field lines that emanate from the X line above the FTE.

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“…The Magnetospheric Multiscale (MMS) mission with its unprecedented high-resolution plasma measurements provides a good opportunity to study the structure of ion-scale flux ropes with a duration of a few seconds in the data (e.g., Alm et al, 2018;Eastwood et al, 2016;Teh et al, 2017;Wang et al, 2017), which present observations of current filaments, nonideal ion behaviors, wave activities and even flux rope coalescence. An ion-scale craterlike flux rope has also been resolved by MMS, which is interpreted as a result of the depression of transverse magnetic fields in a flux rope simulation (Teh et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…The magnetic flux rope is usually regarded as the physical model of the flux transfer event (FTE) (Russell and Elphic, 1978) on Earth's magnetopause, with spatial sizes extending from several ion inertial lengths (d i ) to a few Earth radii (R E ) (e.g., Hasegawa et al, 2010;Eastwood et al, 2016). Recent in situ observations revealed that flux ropes could be flanked by two converging plasma jets, indicating these flux ropes are still active, and possibly generated by multiple, or even sequential, X-line reconnection (Hasegawa et al, 2010;Øieroset et al, 2011;Pu et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Magnetic depression and electron transport in an ion-scale flux rope associated with Kelvin–Helmholtz waves

Tang

Wang

et al. 2018

Ann. Geophys.

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Abstract. We report an ion-scale magnetic flux rope (the size of the flux rope is ∼ 8.5 ion inertial lengths) at the trailing edge of Kelvin-Helmholtz (KH) waves observed by the Magnetospheric Multiscale (MMS) mission on 27 September 2016, which is likely generated by multiple X-line reconnection. The currents of this flux rope are highly filamentary: in the central flux rope, the current flows are mainly parallel to the magnetic field, supporting a local magnetic field increase at about 7 nT, while at the edges the current filaments are predominantly along the antiparallel direction, which induce an opposing field that causes a significant magnetic depression along the axis direction (> 20 nT), meaning the overall magnetic field of this flux rope is depressed compared to the ambient magnetic field. Thus, this flux rope, accompanied by the plasma thermal pressure enhancement in the center, is referred to as a crater type. Intense lower hybrid drift waves (LHDWs) are found at the magnetospheric edge of the flux rope, and the wave potential is estimated to be ∼ 17 % of the electron temperature. Though LHDWs may be stabilized by the mechanism of electron resonance broadening, these waves could still effectively enable diffusive electron transports in the cross-field direction, corresponding to a local density dip. This indicates LHDWs could play important roles in the evolution of crater flux ropes.

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Ion‐scale secondary flux ropes generated by magnetopause reconnection as resolved by MMS

Cited by 97 publications

References 37 publications

Four‐Spacecraft Measurements of the Shape and Dimensionality of Magnetic Structures in the Near‐Earth Plasma Environment

Four‐Spacecraft Measurements of the Shape and Dimensionality of Magnetic Structures in the Near‐Earth Plasma Environment

The substructure of a flux transfer event observed by the MMS spacecraft

Magnetic depression and electron transport in an ion-scale flux rope associated with Kelvin–Helmholtz waves

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