Context and heliographic dependence of heliospheric planar magnetic structures

Jones, G. H.; Balogh, A.

doi:10.1029/2000ja900003

Cited by 30 publications

(42 citation statements)

References 21 publications

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“…They defined a PMS as a period of at least 6 hours during which the interplanetary field experiences large changes of direction, often discontinuously, while remaining within a single plane. Figure 9 of the paper by Jones and Balogh [2000] shows a strong clustering of the PMS normals toward the radial direction. Furthermore, Figure 1 of another paper by Jones and Balogh [2001] demonstrates that when Ulysses was in the fast polar solar wind the rates at which PMS were encountered increased with distance.…”

Section: Discussionmentioning

confidence: 93%

Anisotropy and Alfvénicity of hourly fluctuations in the fast polar solar wind

Neugebauer

2004

J. Geophys. Res.

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[1] Ulysses magnetic and plasma data obtained in the fast polar solar wind are used to study the nature of fluctuations in the frequency range between the turbulent inertial range and the lower-frequency range dominated by quasi-static structures originating at the Sun. For daily variations of hourly averages of the magnetic field components the anisotropy of the fluctuations is less than in the higher-frequency range, and the minimum variance direction loses its alignment with the magnetic field in favor of a more radial direction as the solar distance increases. The anisotropy of the magnetic fluctuations also increases with solar distance, while the Alfvénicity, as measured by the correlation of the field and velocity components, decreases. Most of the observed frequency and distance trends are similar to those observed in fast solar wind streams in the ecliptic, despite the difference in stream structure between high and low latitudes. One major difference from higherfrequency (inertial range) variations at high latitudes is the continuing decline of the correlation between velocity and field vectors between 2 and 4.5 AU. It is suggested that the relative contribution of discontinuities and planar magnetic structures grows with solar distance relative to the contribution of Alfvén waves.

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Section: Discussionmentioning

confidence: 93%

Anisotropy and Alfvénicity of hourly fluctuations in the fast polar solar wind

Neugebauer

2004

J. Geophys. Res.

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“…For CIRs with an identifiable planar magnetic structure, we study their tilt, scale size, and evolution over the solar cycle and the relationship to solar wind deflection. Finally, we examine how the observed local tilt compares with the theoretical predictions of Lee [2000] and Pizzo [1991], as well as with observational results from previous studies [Clack et al, 2000;Gosling and Pizzo, 1999;Jones and Balogh, 2000].…”

Section: Introductionmentioning

confidence: 99%

Formation, shape, and evolution of magnetic structures in CIRs at 1 AU

2012

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[1] We have surveyed the properties of 153 co-rotating interaction regions (CIRs) observed at 1 AU from January, 1995 through December, 2008. We identified that 74 of the 153 CIRs contain planar magnetic structures (PMSs). For planar and non-planar CIRs, we compared distributions of the bulk plasma and magnetic field parameters. Our identification of CIRs and their features yields the following results: (1) The different pressures within CIRs are strongly correlated. (2) There is no statistical difference between planar and non-planar CIRs in the distributions and correlations between bulk plasma and magnetic field parameters. (3) The mean observed CIR azimuthal tilt is within 1 s of the predicted Parker spiral at 1 AU, while the mean meridional tilt is about 20°. (4) The meridional tilt of CIRs changes from one solar rotation to the next, with no relationship between successive reoccurrences. (5) The meridional tilt of CIRs in the ecliptic is not ordered by the magnetic field polarity of the parent coronal hole. (6) Although solar wind deflection is a function of CIR shape and speed, the relationship is not in agreement with that predicted by Lee (2000). We conclude the following: (1) PMSs in CIRs are not caused by a unique characteristic in the local plasma or magnetic field. (2) The lack of relationship between CIR tilt and its parent coronal hole suggests that coronal hole boundaries may be more complex than currently observed. (3) In general, further theoretical work is necessary to explain the observations of CIR tilt.

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“…These are periods when the variations of the magnetic field occur parallel to a single plane. PMSs are identified in most sheath regions and they typically cover a considerable part of the sheath (e.g., Jones and Balogh 2000;Palmerio et al 2016). Another key mechanism that gives rise to PMSs in ICME sheaths is the amplification and alignment of pre-existing solar wind discontinuities at the ICMEdriven shock.…”

Section: Large-scale Sheath Structuresmentioning

confidence: 99%

Coronal mass ejections and their sheath regions in interplanetary space

Kilpua

Koskinen

Pulkkinen

2017

Living Rev Sol Phys

371

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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Context and heliographic dependence of heliospheric planar magnetic structures

Cited by 30 publications

References 21 publications

Anisotropy and Alfvénicity of hourly fluctuations in the fast polar solar wind

Anisotropy and Alfvénicity of hourly fluctuations in the fast polar solar wind

Formation, shape, and evolution of magnetic structures in CIRs at 1 AU

Coronal mass ejections and their sheath regions in interplanetary space

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