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 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 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 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

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.

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>

Activated Prominences; Mechanisms for Activation and Eruption

1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer
Keyword(s):  
Pressure Gradient ◽  
Density Gradient ◽  
Current Density ◽  
Convective Instability ◽  
Tearing Mode ◽  
Magnetic Shear ◽  
Long Wavelength ◽  
Ideal Mhd ◽  
Gradient Change ◽  
Accelerated Particles

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.

scholarly journals The Location of Magnetic Reconnection at Earth’s Magnetopause

2021 ◽  
Vol 217 (3) ◽  
Author(s):  
K. J. Trattner ◽  
S. M. Petrinec ◽  
S. A. Fuselier
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Ion Beams ◽  
Review Article ◽  
Observational Evidence ◽  
Magnetic Shear ◽  
General Direction ◽  
Shear Model ◽  
Wide Range

AbstractOne of the major questions about magnetic reconnection is how specific solar wind and interplanetary magnetic field conditions influence where reconnection occurs at the Earth’s magnetopause. There are two reconnection scenarios discussed in the literature: a) anti-parallel reconnection and b) component reconnection. Early spacecraft observations were limited to the detection of accelerated ion beams in the magnetopause boundary layer to determine the general direction of the reconnection X-line location with respect to the spacecraft. An improved view of the reconnection location at the magnetopause evolved from ionospheric emissions observed by polar-orbiting imagers. These observations and the observations of accelerated ion beams revealed that both scenarios occur at the magnetopause. Improved methodology using the time-of-flight effect of precipitating ions in the cusp regions and the cutoff velocity of the precipitating and mirroring ion populations was used to pinpoint magnetopause reconnection locations for a wide range of solar wind conditions. The results from these methodologies have been used to construct an empirical reconnection X-line model known as the Maximum Magnetic Shear model. Since this model’s inception, several tests have confirmed its validity and have resulted in modifications to the model for certain solar wind conditions. This review article summarizes the observational evidence for the location of magnetic reconnection at the Earth’s magnetopause, emphasizing the properties and efficacy of the Maximum Magnetic Shear Model.

Sign in / Sign up

Export Citation Format

Share Document