The relationship between ELF-VHF waves and magnetic shear at the dayside magnetopause

1996 ◽  
Vol 23 (7) ◽  
pp. 773-776 ◽  
Author(s):  
Z. Zhu ◽  
P. Song ◽  
J. F. Drake ◽  
C. T. Russell ◽  
R. R. Anderson ◽  
...  
Keyword(s):  
Magnetic Shear ◽  
Dayside Magnetopause ◽  
The Relationship

scholarly journals Double Star TC-1 observations of component reconnection at the dayside magnetopause: a preliminary study

2005 ◽  
Vol 23 (8) ◽  
pp. 2889-2895 ◽  
Author(s):  
Z. Y. Pu ◽  
C. J. Xiao ◽  
X. G. Zhang ◽  
Z. Y. Huang ◽  
S. Y. Fu ◽  
...  
Keyword(s):  
Double Star ◽  
Flow Reversal ◽  
Low Latitude ◽  
Magnetic Shear ◽  
Guide Field ◽  
Dayside Magnetopause ◽  
Preliminary Study ◽  
Reconnection Site ◽  
Quadrupolar Field

Abstract. In spring 2004 Double Star TC-1 measured a number of reconnection signatures at the dayside low-latitude magnetopause (MP) when there was a notable By component in the magnetosheath. In a number of events we can show that reconnection was operating nearby TC-1 in the subsolar MP region. In this paper we describe three representative events: (a) event on 21 March 2004 in which the reconnection site can be remotely monitored, the spacecraft was passing by the X-line; (b) event on 12 March 2004 in which TC-1 observed the magnetospheric part of the quadrupolar field, together with a consistent flow reversal; (c) event on 26 March 2004 which occurred for northward IMF, TC-1 observed a reversal of vy across the equatorial MP. In these events the shear angles across the MP were considerably smaller than 180°; a noticeable guide field was present. These observations are consistent with near equatorial component merging, suggesting that component reconnection preferably occurs at the dayside low-latitude MP. There is evidence that when a pronounced magnetic shear across the MP exists in the By component, reconnection may operate at the dayside low-latitude MP for northward IMF Bz.

The Relationship between Magnetic Gradient and Magnetic Shear in Five Super Active Regions Producing Great Flares

2006 ◽  
Vol 6 (4) ◽  
pp. 477-488 ◽  
Author(s):  
Hai-Min Wang ◽  
Hui Song ◽  
Ju Jing ◽  
Vasyl Yurchyshyn ◽  
Yuan-Yong Deng ◽  
...  
Keyword(s):  
Active Regions ◽  
Magnetic Shear ◽  
Magnetic Gradient ◽  
The Relationship

scholarly journals Ion acceleration dependence on magnetic shear angle in dayside magnetopause reconnection

2015 ◽  
Vol 120 (9) ◽  
pp. 7255-7269 ◽  
Author(s):  
S. K. Vines ◽  
S. A. Fuselier ◽  
K. J. Trattner ◽  
S. M. Petrinec ◽  
J. F. Drake
Keyword(s):  
Shear Angle ◽  
Ion Acceleration ◽  
Magnetic Shear ◽  
Dayside Magnetopause ◽  
Magnetopause Reconnection

Structure of the dayside magnetopause for low magnetic shear

1993 ◽  
Vol 98 (A8) ◽  
pp. 13409-13422 ◽  
Author(s):  
G. Paschmann ◽  
W. Baumjohann ◽  
N. Sckopke ◽  
T. -D. Phan ◽  
H. Lühr
Keyword(s):  
Magnetic Shear ◽  
Dayside Magnetopause

scholarly journals IMF control of cusp proton emission intensity and dayside convection: implications for component and anti-parallel reconnection

2003 ◽  
Vol 21 (4) ◽  
pp. 955-982 ◽  
Author(s):  
M. Lockwood ◽  
B. S. Lanchester ◽  
H. U. Frey ◽  
K. Throp ◽  
S. K. Morley ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Wind Plasma ◽  
High Time Resolution ◽  
Proton Emission ◽  
Dayside Magnetopause ◽  
Propagation Delays ◽  
Wind Spacecraft ◽  
Upstream Solar Wind ◽  
The Relationship ◽  
The Imf

Abstract. We study a brightening of the Lyman-a emission in the cusp which occurred in response to a short-lived south-ward turning of the interplanetary magnetic field (IMF) during a period of strongly enhanced solar wind plasma concentration. The cusp proton emission is detected using the SI-12 channel of the FUV imager on the IMAGE spacecraft. Analysis of the IMF observations recorded by the ACE and Wind spacecraft reveals that the assumption of a constant propagation lag from the upstream spacecraft to the Earth is not adequate for these high time-resolution studies. The variations of the southward IMF component observed by ACE and Wind allow for the calculation of the ACE-to-Earth lag as a function of time. Application of the derived propagation delays reveals that the intensity of the cusp emission varied systematically with the IMF clock angle, the relationship being particularly striking when the intensity is normalised to allow for the variation in the upstream solar wind proton concentration. The latitude of the cusp migrated equatorward while the lagged IMF pointed southward, confirming the lag calculation and indicating ongoing magnetopause reconnection. Dayside convection, as monitored by the SuperDARN network of radars, responded rapidly to the IMF changes but lagged behind the cusp proton emission response: this is shown to be as predicted by the model of flow excitation by Cowley and Lockwood (1992). We use the numerical cusp ion precipitation model of Lockwood and Davis (1996), along with modelled Lyman-a emission efficiency and the SI-12 instrument response, to investigate the effect of the sheath field clock angle on the acceleration of ions on crossing the dayside magnetopause. This modelling reveals that the emission commences on each reconnected field line 2–2.5 min after it is opened and peaks 3–5 min after it is opened. We discuss how comparison of the Lyman-a intensities with oxygen emissions observed simultaneously by the SI-13 channel of the FUV instrument offers an opportunity to test whether or not the clock angle dependence is consistent with the "component" or the "anti-parallel" reconnection hypothesis.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; solar wind-magnetosphere interactions) – Space plasma physics (magnetic reconnection)

scholarly journals The azimuthal extent of three flux transfer events

2008 ◽  
Vol 26 (8) ◽  
pp. 2353-2369 ◽  
Author(s):  
R. C. Fear ◽  
S. E. Milan ◽  
A. N. Fazakerley ◽  
E. A. Lucek ◽  
S. W. H. Cowley ◽  
...  
Keyword(s):  
Flux Tube ◽  
Time Varying ◽  
Magnetic Shear ◽  
Simple Interpretation ◽  
Flux Transfer Events ◽  
Dayside Magnetopause ◽  
In Situ Observations ◽  
Flux Transfer ◽  
Separation Size

Abstract. In early 2006, the Cluster spacecraft crossed the dayside magnetopause twice each orbit with the spacecraft at their largest separation of the entire mission (~10 000 km). In this paper, we present in situ observations at this separation size of flux transfer events (FTEs), which are a signature of transient or time-varying magnetopause reconnection. We study a magnetopause crossing on 27 January 2006; for half an hour, the tetrahedron of Cluster spacecraft straddled the magnetopause and during this time a large number of flux transfer events were observed. Three particular FTEs were observed by all four spacecraft, enabling it to be shown that individual FTEs at the magnetopause can extend azimuthally for at least 10 000 km. By combining the Cluster tetrahedron geometry with the observed velocity of the FTEs, it can be shown that the poleward extent of one FTE is significantly smaller than its azimuthal extent. The location of the Cluster spacecraft when they observed this FTE suggests that it is inconsistent with the simple interpretation of an "elbow-shaped" flux tube. The FTE's azimuthal extent suggests that it was more likely generated at a comparatively long reconnection line or lines, although the magnetic shear across the magnetopause is not high enough to exclude the "elbow-shaped" model entirely.

Dependence of fishbone cycle on energetic particle intensity in EAST low-magnetic-shear plasmas

2020 ◽  
Vol 86 (6) ◽  
Author(s):  
Xiang Zhu ◽  
Long Zeng ◽  
Zhiyong Qiu ◽  
Baolong Hao ◽  
Wei Shen ◽  
...  
Keyword(s):  
Energetic Particle ◽  
Pressure Ratio ◽  
Magnetic Shear ◽  
Cycle Frequency ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Power Simulation ◽  
Particle Pressure ◽  
Particle Intensity ◽  
The Relationship

The dependence of fishbone cycle on energetic particle intensity has been investigated in EAST low-magnetic-shear plasmas. It is observed that the fishbone mode growth rate, saturation amplitude as well as fishbone cycle frequency clearly increase with increasing neutral beam injection (NBI) power. Moreover, enhanced electron density and temperature perturbations as well as energetic particle loss were observed with greater injected NBI power. Simulation results using M3D-K code show that as the NBI power increases, the resonant frequency and the energy of the resonant particles become higher, and the saturation amplitude of the mode also changes, due to the non-perturbative energetic particle contribution. The relationship between the calculated energetic particle pressure ratio and fishbone cycle frequency is obtained as ${f_{\textrm{FC}}} = 2.2{(1000{\beta _{\textrm{ep,calc}}} - 0.1)^{5.9 \pm 0.5}}$ . Results consistent with the experimental observations have been achieved based on a predator–prey model.

The location of Component Reconnection at the Earth’s Magnetopause During Dominant IMF By and Large Dipole Tilt Conditions

2020 ◽  
Author(s):  
Karlheinz Trattner ◽  
Stephen Fuselier ◽  
Steven Petrinec ◽  
James Burch ◽  
Paul Cassak ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Magnetic Energy ◽  
Magnetic Shear ◽  
The Earth ◽  
Laboratory Plasmas ◽  
Reconnection Region ◽  
Dayside Magnetopause ◽  
Field Lines ◽  
Dipole Tilt

<p>The interplanetary magnetic field (IMF) convected with the solar wind drapes around the region of space dominated by Earth’s geomagnetic field and undergoes a process called magnetic reconnection at the magnetopause; the boundary layer that separates these two distinct regimes. Magnetic reconnection changes the topology of magnetic field lines and is known to convert magnetic energy into kinetic energy and heat. This fundamental process occurs in many environments, spanning from laboratory plasmas to the heliosphere, the solar atmosphere, and to astrophysical phenomena. Magnetic reconnection at the Earth’s magnetopause has been observed at various times and places as either anti-parallel and/or component reconnection. A model known as the Maximum Magnetic Shear Model combines these two scenarios, creating long reconnection lines crossing the dayside magnetopause along a ridge of maximum magnetic shear. <br>The connection points between the anti-parallel and the component reconnection segments of the reconnection line are known as ‘Knee’ regions. Using observations from the MMS satellites, it was shown that the location of the Knee region depends strongly on the local draping conditions of the IMF across the magnetopause, with certain draping conditions causing a deflection of the location along the anti-parallel reconnection region. This study discusses an event that shows that the entire component reconnection X-line crossing the dayside magnetopause can be affected by this deflection. This result emphasizes the importance of anti-parallel reconnection that seems to control where component reconnection is occurring. </p>

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