The Wind magnetic cloud and events of October 18–20, 1995: Interplanetary properties and as triggers for geomagnetic activity

Lepping, R. P.; Burlaga, L. F.; Szabó, Á.; Ogilvie, K. W.; Mish, W. H.; Vassiliadis, D.; Lazarus, A. J.; Steinberg, J. T.; Farrugia, C. J.; Janoo, L.; Mariani, F.

doi:10.1029/97ja00272

Cited by 145 publications

(144 citation statements)

References 53 publications

Supporting

Mentioning

137

Contrasting

Order By: Relevance

“…Magnetic modeling of the observations showed that the cloud could be well approximated with a flux rope of right-handed twist (positive helicity; Lepping et al 1997). It was proposed by van Driel-Gesztelyi et al (2000) that the magnetic cloud was launched from AR 7912: the positive (right-handed) twist of the cloud agreed with the sign of the twist in the expanding coronal loops as indicated by their forward S-shape.…”

Section: The Active Region Noaa 7912 and The Ldementioning

confidence: 62%

Global budget for an eruptive active region

Bleybel¹,

Amari²,

Driel‐Gesztelyi³

et al. 2002

A&A

View full text Add to dashboard Cite

Abstract. We present results on the magnetic structure of NOAA Active Region #7912 which was involved in a long duration flare on 14 October 1995, and was the source region for a magnetic cloud observed by the WIND spacecraft from October 18-20. Using vector magnetograms from the Imaging Vector Magnetograph ("IVM"), we reconstruct the magnetic field above this active region, assuming it is in a non-linear force-free state. This reconstruction is used to determine global properties of the active region magnetic field including topology, magnetic energy, and relative magnetic helicity. A comparison of some global quantities before and after the eruptive event is discussed. We show that the magnetic energy and relative helicity of the active region decreased after the eruption, consistent with the ejection of a large amount of helicity (in the magnetic cloud). We also show that the relaxed post-flare state still contains nonlinearities and is not consistent with a linear force-free state as predicted by Taylor's theory of relaxation. These results agree with those of recent numerical simulations concerning plasmoid ejection and helicity redistribution in the disruption of magnetic configurations. We propose as an explanation that the anchoring of field lines in the photosphere prevents a full cascade to the Taylor state, and that a variational formulation in which the action functional would describe this constraint should be derived.

show abstract

Section: The Active Region Noaa 7912 and The Ldementioning

confidence: 62%

Global budget for an eruptive active region

Bleybel¹,

Amari²,

Driel‐Gesztelyi³

et al. 2002

A&A

View full text Add to dashboard Cite

show abstract

“…The factors that control the CME-CME interactions are not yet well understood but the details should depend, e.g., on their relative launch direction, timing, speed and the magnetic field orientation (e.g., Lugaz et al 2013). An ICME shock that is overtaking the preceding ICME can additionally compress the magnetic field within the ICME (Burlaga 1991;Lepping et al 1997). Fig.…”

Section: Observations Of Icme Interactions In the Heliospherementioning

confidence: 99%

Coronal mass ejections and their sheath regions in interplanetary space

Kilpua

Koskinen

Pulkkinen

2017

Living Rev Sol Phys

371

360

View full text Add to dashboard Cite

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.

show abstract

“…However, this rotation is not always smooth and often exhibits both small-and large-scale fluctuations of the magnetic field within the cloud [Crooker et al, 1990]. Various physical processes have been proposed that may influence the topology of a magnetic cloud, both near to the Sun and further out in the heliosphere, including magnetic reconnection [Gosling et al, 2007], interaction between multiple magnetic flux ropes [e.g., Fainberg et al, 1996;Lepping et al, 1997;Osherovich et al, 1999;Farrugia, 2001], spontaneous formation of current sheets [Owens, 2009], or interaction with dust trails originating from comets [Russell et al, 2009].…”

Section: Introductionmentioning

confidence: 99%

Investigating the observational signatures of magnetic cloud substructure

et al. 2011

View full text Add to dashboard Cite

[1] Magnetic clouds (MCs) represent a subset of interplanetary coronal mass ejections (ICMEs) that exhibit a magnetic flux rope structure. They are primarily identified by smooth, large-scale rotations of the magnetic field. However, both small-and large-scale fluctuations of the magnetic field are observed within some magnetic clouds. We analyzed the magnetic field in the frames of the flux ropes, approximated using a minimum variance analysis (MVA), and have identified a small number of MCs within which multiple reversals of the gradient of the azimuthal magnetic field are observed. We herein use the term "substructure" to refer to regions that exhibit this signature. We examine, in detail, one such MC observed on 13 April 2006 by the ACE and WIND spacecraft and show that substructure has distinct signatures in both the magnetic field and plasma observations. We identify two thin current sheets within the substructure and find that they bound the region in which the observations deviate most significantly from those typically expected in MCs. The majority of these clouds are followed by fast solar wind streams, and a comparison of the properties of this magnetic cloud with five similar events reveals that they have lower nondimensional expansion rates than nonovertaken magnetic clouds. We discuss and evaluate several possible explanations for this type of substructure, including the presence of multiple flux ropes and warping of the MC structure, but we conclude that none of these scenarios is able to fully explain all of the aspects of the substructure observations.

show abstract

The Wind magnetic cloud and events of October 18–20, 1995: Interplanetary properties and as triggers for geomagnetic activity

Cited by 145 publications

References 53 publications

Global budget for an eruptive active region

Global budget for an eruptive active region

Coronal mass ejections and their sheath regions in interplanetary space

Investigating the observational signatures of magnetic cloud substructure

Contact Info

Product

Resources

About