Does a Local B-Minimum Appear in the Tail Current Sheet During a Substorm Growth Phase?

2018 ◽  
Vol 45 (6) ◽  
pp. 2566-2573 ◽  
Author(s):  
V. A. Sergeev ◽  
E. I. Gordeev ◽  
V. G. Merkin ◽  
M. I. Sitnov
Keyword(s):  
Current Sheet ◽  
Growth Phase ◽  
Tail Current

Current carriers in the near-Earth cross-tail current sheet during substorm growth phase

1990 ◽  
Vol 17 (5) ◽  
pp. 583-586 ◽  
Author(s):  
D. G. Mitchell ◽  
D. J. Williams ◽  
C. Y. Huang ◽  
L. A. Frank ◽  
C. T. Russell
Keyword(s):  
Current Sheet ◽  
Growth Phase ◽  
Tail Current

scholarly journals Detecting near-tail current sheet formation using isotropic boundaries: lessons from global MHD.

2020 ◽  
Author(s):  
E.I. Gordeev ◽  
Keyword(s):  
Current Sheet ◽  
Growth Phase ◽  
Energetic Particles ◽  
Lessons Learned ◽  
Mhd Simulation ◽  
Tail Current ◽  
Different Types ◽  
Global Mhd Simulation ◽  
Orbiting Spacecraft ◽  
Magnetotail Current Sheet

A number of recent studies suggests an existence of magnetotail current sheet configurations with tailward Bz gradient during the growth phase of the substorm. Such configurations are especially interesting since they are potentially unstable for different types of instabilities and can lead to explosive reconfiguration of the magnetosphere. However, the observations are rare and ability to observe tailward gradients is very limited. Here we use the global MHD configuration with near-tail Bz minimum to investigate the regions with adiabatic and non-adiabatic behavior of energetic particles. Thus we estimate the locations of the isotropic boundaries for the modelled POES-type spacecraft flybys. We expect that the lessons learned from global MHD simulation may become helpful in exploration of non-monotonic tail current sheet configuration using observations on low-orbiting spacecraft.

Global and local processes of thin current sheet formation during substorm growth phase

2021 ◽  
pp. 105671
Author(s):  
A. Runov ◽  
V. Angelopoulos ◽  
A.V. Artemyev ◽  
J.M. Weygand ◽  
S. Lu ◽  
...  
Keyword(s):  
Current Sheet ◽  
Growth Phase ◽  
Thin Current Sheet ◽  
Global And Local

The near-Earth cross-tail current sheet: Detailed ISEE 1 and 2 case studies

1986 ◽  
Vol 91 (A4) ◽  
pp. 4287 ◽  
Author(s):  
D. J. McComas ◽  
C. T. Russell ◽  
R. C. Elphic ◽  
S. J. Bame
Keyword(s):  
Current Sheet ◽  
Case Studies ◽  
Tail Current

The Geosynchronous Substorm

1996 ◽  
Author(s):  
Charles F. Kennel
Keyword(s):  
Magnetic Field ◽  
Growth Phase ◽  
Large Scale ◽  
Current System ◽  
Dynamic Pressure ◽  
Geosynchronous Orbit ◽  
Sudden Increase ◽  
Tail Current ◽  
Tightly Coupled ◽  
The Cross

The reconnection model of substorms deals with the large-scale changes in the structure of the magnetosphere and tail as convection intensifies following a sudden increase in the dayside reconnection rate. The model has difficulty making statements relevant to the small scales that characterize auroral onset. However, there has been considerable progress in assembling high-resolution observations of the events in space that now appear to be tightly coupled to the dramatic auroral events that first defined the term substorm. We will call this clear and consistent ensemble the geosynchronous model of substorms, since most of it was first conceived from observations made on geostationary spacecraft. We will also include in this ensemble the recent observations made using the quasigeostationary spacecraft, AMPTE/CCE, and so, by the geosynchronous substorm, we really mean the substorm as it appears on the earth's nightside typically between 6 and, say, 10 RE downtail. The earth’s magnetic field at geosynchronous orbit is about 100 nT, some three times larger than in the tail lobes. Study of quiet field intervals singles out the dependence of the geosynchronous field on solar wind dynamic pressure, since the modulation due to changes in the direction of the interplanetary field is presumably negligible during quiet conditions. The periodic variations in the quiet field depend on local time, season, and orientation of the earth’s dipole axis relative to spacecraft location (McPherron and Barfield, 1980; Rufenach et al., 1992). Superposed on the quiet field are perturbations up to about 50 nT due to several magnetospheric current systems, including the magnetopause current, the ring current, and the cross-tail current; the most striking are due to changes in the cross-tail current system. Observations from geosynchronous orbit were the first to indicate that the nightside magnetic field becomes more “tail-like” during substorm growth phase, and more dipolar during the expansion phase. This simple observation is the foundation on which today’s elaborate geosynchronous substorm model rests. The geosynchronous field becomes progressively more “tail-like” as the cross-tail current system intensifies and/or moves earthward during the substorm growth phase (McPherron et al., 1975; Coleman and McPherron, 1976; McPherron, 1979; Kauffmann, 1987).

Growth-phase thinning of the near-Earth current sheet during the CDAW 6 substorm

1994 ◽  
Vol 99 (A4) ◽  
pp. 5805 ◽  
Author(s):  
Jeff Sanny ◽  
R. L. McPherron ◽  
C. T. Russell ◽  
D. N. Baker ◽  
T. I. Pulkkinen ◽  
...  
Keyword(s):  
Current Sheet ◽  
Growth Phase

scholarly journals Global properties of magnetotail current sheet flapping: THEMIS perspectives

2009 ◽  
Vol 27 (1) ◽  
pp. 319-328 ◽  
Author(s):  
A. Runov ◽  
V. Angelopoulos ◽  
V. A. Sergeev ◽  
K.-H. Glassmeier ◽  
U. Auster ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Growth Phase ◽  
Timing Analysis ◽  
Wave Length ◽  
Global Properties ◽  
The Cross ◽  
Magnetic Field Variations ◽  
The Magnetic Field ◽  
Magnetotail Current Sheet

Abstract. A sequence of magnetic field oscillations with an amplitude of up to 30 nT and a time scale of 30 min was detected by four of the five THEMIS spacecraft in the magnetotail plasma sheet. The probes P1 and P2 were at X=−15.2 and −12.7 RE and P3 and P4 were at X=−7.9 RE. All four probes were at −6.5>Y>−7.5 RE (major conjunction). Multi-point timing analysis of the magnetic field variations shows that fronts of the oscillations propagated flankward (dawnward and Earthward) nearly perpendicular to the direction of the magnetic maximum variation (B1) at velocities of 20–30 km/s. These are typical characteristics of current sheet flapping motion. The observed anti-correlation between ∂B1/∂t and the Z-component of the bulk velocity make it possible to estimate a flapping amplitude of 1 to 3 RE. The cross-tail scale wave-length was found to be about 5 RE. Thus the flapping waves are steep tail-aligned structures with a lengthwise scale of >10 RE. The intermittent plasma motion with the cross-tail velocity component changing its sign, observed during flapping, indicates that the flapping waves were propagating through the ambient plasma. Simultaneous observations of the magnetic field variations by THEMIS ground-based magnetometers show that the flapping oscillations were observed during the growth phase of a substorm.

scholarly journals Current carriers in the bifurcated tail current sheet: Ions or electrons?

2008 ◽  
Vol 113 (A4) ◽  
pp. n/a-n/a ◽  
Author(s):  
P. L. Israelevich ◽  
A. I. Ershkovich ◽  
R. Oran
Keyword(s):  
Current Sheet ◽  
Tail Current
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