Magnetic storms: Current understanding and outstanding questions

Kamide, Y.; McPherron, R. L.; González, W. D.; Hamilton, D. C.; Hudson, H. S.; Joselyn, Jo Ann; Kahler, S. W.; Lyons, L. R.; Lundstedt, H.; Szuszczewicz, E. P.

doi:10.1029/gm098p0001

Cited by 52 publications

(43 citation statements)

References 46 publications

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“…18 and 19, sheaths have many properties that enhance solar wind-magnetosphere coupling efficiency (see the detailed discussion of this topic in Kilpua et al 2017); high dynamic pressure (e.g., Palmroth et al 2007;Myllys et al 2016), enhanced ULF wave power causing enhanced viscous interactions at the magnetopause (e.g., Borovsky and Funsten 2003) and high Alfvén Mach numbers causing stronger compression of the plasma and field at the bow shock and the cross polar cap potential saturating at larger driving electric fields than during low Alfvén Mach number conditions (e.g., Borovsky and Birn 2014;Myllys et al 2016). Largescale fluctuations in the IMF north-south component could also build the ring current up more efficiently than a smoother driver of similar magnitude due to periodic trapping of the particles in the ring current region (e.g., Kamide et al 1997 . The geomagnetic storm definition follows NOAA storm scale (http://www.swpc.…”

Section: Icmes/sheaths As Drivers Of Storms In the Magnetospherementioning

confidence: 99%

Coronal mass ejections and their sheath regions in interplanetary space

Kilpua

Koskinen

Pulkkinen

2017

Living Rev Sol Phys

373

360

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Interplanetary coronal mass ejections (ICMEs) are large-scale heliospheric transients that originate from the Sun. When an ICME is sufficiently faster than the preceding solar wind, a shock wave develops ahead of the ICME. The turbulent region between the shock and the ICME is called the sheath region. ICMEs and their sheaths and shocks are all interesting structures from the fundamental plasma physics viewpoint. They are also key drivers of space weather disturbances in the heliosphere and planetary environments. ICME-driven shock waves can accelerate charged particles to high energies. Sheaths and ICMEs drive practically all intense geospace storms at the Earth, and they can also affect dramatically the planetary radiation environments and atmospheres. This review focuses on the current understanding of observational signatures and properties of ICMEs and the associated sheath regions based on five decades of studies. In addition, we discuss modelling of ICMEs and many fundamental outstanding questions on their origin, evolution and effects, largely due to the limitations of single spacecraft observations of these macro-scale structures. We also present current understanding of space weather consequences of these large-scale solar wind structures, including effects at the other Solar System planets and exoplanets. We specially emphasize the different origin, properties and consequences of the sheaths and ICMEs.

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Section: Icmes/sheaths As Drivers Of Storms In the Magnetospherementioning

confidence: 99%

Coronal mass ejections and their sheath regions in interplanetary space

Kilpua

Koskinen

Pulkkinen

2017

Living Rev Sol Phys

373

360

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“…Obviously strong substorms occurring during the storm recovery phase do not in¯uence the ring current decay. This is in accor- Kamide et al (1998). As Fig.…”

Section: Westward Electrojetmentioning

confidence: 82%

About the relationship between auroral electrojets and ring currents

Grafe

Feldstein

2000

Ann. Geophys.

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Abstract.The relationship between the storm-time ring current and the auroral electrojets is investigated using IMAGE magnetometer data, D St and H-SYM, and solar wind data. Statistical results as well as the investigation of single events show that the auroral electrojets occur also during nonstorm conditions without storm-time ring current development and even during the storm recovery phase of increasing D St . A close correlation between electrojet intensity and ring current intensity was not found. Though the eastward electrojet moves equatorward during the storm main phase there is no unequivocal relationship between the movement of the westward electrojet and the ring current development. All these results suggest that the auroral electrojets and the ring current develop more or less independently of each other.

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“…This indicates that substorms are not fundamental to the injection of ring current particles to L<4 (Tsurutani et al, 1997). On the other hand, it has been found that there is a one-to-one relation between intense (D st <−100 nT) storms and large negative IMF B z (<−10 nT) that lasts for at least 3 h (Kamide et al, 1997). Numerical calculations show that the intense magnetospheric convection electric field E C can effectively energize (within 2 to 3 h) charged particles while they are injected from the magnetotail to the ring current region (L∼3).…”

Section: Introductionmentioning

confidence: 99%

Energetic ion injection and formation of the storm-time symmetric ring current

Xie

Zhou

et al. 2006

Ann. Geophys.

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Abstract. An extensive study of ring current injection and intensification of the storm-time ring current is conducted with three-dimensional (3-D) test particle trajectory calculations (TPTCs). The TPTCs reveal more accurately the process of ring current injection, with the main results being the following: (1) an intense convection electric field can effectively energize and inject plasma sheet particles into the ring current region within 1-3 h. (2) Injected ions often follow chaotic trajectories in non-adiabatic regions, which may have implications in storm and ring current physics. (3) The shielding electric field, which arises as a consequence of enhanced convection and co-exists with the injection and convection electric field, may cause the original open trajectories of injected ions with higher energy to change into closed ones, thus playing a role in the formation of the symmetric ring current.

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Magnetic storms: Current understanding and outstanding questions

Cited by 52 publications

References 46 publications

Coronal mass ejections and their sheath regions in interplanetary space

Coronal mass ejections and their sheath regions in interplanetary space

About the relationship between auroral electrojets and ring currents

Energetic ion injection and formation of the storm-time symmetric ring current

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