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Dipolarization fronts as earthward propagating flux ropes: A three-dimensional global hybrid simulation

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dc.creatorLu, San
dc.creatorLu, Quanming
dc.creatorLin, Yu
dc.creatorWang, Xueyi
dc.creatorGe, Yasong
dc.creatorWang, Rongsheng
dc.creatorZhou, Meng
dc.creatorFu, Huishan
dc.creatorHuang, Can
dc.creatorWu, Mingyu
dc.creatorWang, Shui
dc.description.abstractDipolarization fronts (DFs) as earthward propagating flux ropes (FRs) in the Earth's magnetotail are presented and investigated with a three-dimensional (3-D) global hybrid simulation for the first time. In the simulation, several small-scale earthward propagating FRs are found to be formed by multiple X line reconnection in the near tail. During their earthward propagation, the magnetic field B-z of the FRs becomes highly asymmetric due to the imbalance of the reconnection rates between the multiple X lines. At the later stage, when the FRs approach the near-Earth dipole-like region, the antireconnection between the southward/negative B-z of the FRs and the northward geomagnetic field leads to the erosion of the southward magnetic flux of the FRs, which further aggravates the B-z asymmetry. Eventually, the FRs merge into the near-Earth region through the antireconnection. These earthward propagating FRs can fully reproduce the observational features of the DFs, e.g., a sharp enhancement of B-z preceded by a smaller amplitude B-z dip, an earthward flow enhancement, the presence of the electric field components in the normal and dawn-dusk directions, and ion energization. Our results show that the earthward propagating FRs can be used to explain the DFs observed in the magnetotail. The thickness of the DFs is on the order of several ion inertial lengths, and the electric field normal to the front is found to be dominated by the Hall physics. During the earthward propagation from the near-tail to the near-Earth region, the speed of the FR/DFs increases from similar to 150km/s to similar to 1000km/s. The FR/DFs can be tilted in the GSM (x,y) plane with respect to the y (dawn-dusk) axis and only extend several Earth radii in this direction. Moreover, the structure and evolution of the FRs/DFs are nonuniform in the dawn-dusk direction, which indicates that the DFs are essentially 3-D.en_US
dc.publisherAmerican Geophysical Unionen_US
dc.rights©American Geophysical Union 2015. This is this the version of record co-published by the American Geophysical Union and John Wiley & Sons, Inc. It is made available under the CC-BY-NC-ND 4.0 license. Item should be cited as: Lu, San, et al. "Dipolarization fronts as earthward propagating flux ropes: A three‐dimensional global hybrid simulation." Journal of Geophysical Research: Space Physics 120.8 (2015): 6286-6300.en_US
dc.titleDipolarization fronts as earthward propagating flux ropes: A three-dimensional global hybrid simulationen_US
dc.type.genreJournal Article, Academic Journalen_US

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