scholarly journals Current sheet bending as destabilizing factor in magnetotail dynamics

2018 ◽  
Vol 25 (9) ◽  
pp. 092901 ◽  
Author(s):  
D. B. Korovinskiy ◽  
V. S. Semenov ◽  
N. V. Erkaev ◽  
I. B. Ivanov ◽  
S. A. Kiehas
Keyword(s):  
Current Sheet ◽  
Sheet Bending ◽  
Magnetotail Dynamics

scholarly journals Dynamics of Variable Dusk-Dawn Flow Associated with Magnetotail Current Sheet Flapping

2021 ◽  
Author(s):  
James Henry Lane ◽  
Adrian Grocott ◽  
Nathan Anthony Case ◽  
Maria-Theresia Walach
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Field Data ◽  
Large Scale ◽  
Magnetic Field Data ◽  
Analysis Technique ◽  
Upstream Solar Wind ◽  
Magnetotail Dynamics ◽  
Magnetotail Current Sheet

Abstract. Previous observations have provided a clear indication that the dusk-dawn (v⊥y) sense of both slow (< 200 km s−1) and fast (> 200 km s−1) convective magnetotail flows is strongly governed by the Interplanetary Magnetic Field (IMF) By conditions. The related “untwisting hypothesis” of magnetotail dynamics is commonly invoked to explain this dependence, in terms of a large-scale magnetospheric asymmetry. In the current study, we present Cluster spacecraft observations from 12 October 2006 of earthward convective magnetotail plasma flows whose dusk-dawn sense disagrees with the untwisting hypothesis of IMF By control of the magnetotail flows. During this interval, observations of the upstream solar wind conditions from OMNI, and ionospheric convection data using SuperDARN, indicate a large-scale magnetospheric morphology consistent with positive IMF By penetration into the magnetotail. Inspection of the in-situ Cluster magnetic field data reveals a flapping of the magnetotail current sheet; a phenomenon known to influence dusk-dawn flow. Results from the curlometer analysis technique suggest that the dusk-dawn flow perturbations may have been driven by the J x B force associated with a dawnward-propagating flapping of the magnetotail current sheet, locally overriding the expected IMF By control of the flows. We conclude that invocation of the untwisting hypothesis may be inappropriate when interpreting intervals of dynamic magnetotail behaviour such as during current sheet flapping.

scholarly journals On application of asymmetric Kan-like exact equilibria to the Earth magnetotail modeling

2018 ◽  
Vol 36 (2) ◽  
pp. 641-653 ◽  
Author(s):  
Daniil B. Korovinskiy ◽  
Darya I. Kubyshkina ◽  
Vladimir S. Semenov ◽  
Marina V. Kubyshkina ◽  
Nikolai V. Erkaev ◽  
...  
Keyword(s):  
Current Sheet ◽  
Vertical Plane ◽  
Magnetic Flux Tube ◽  
Model Parameters ◽  
Specific Class ◽  
The Earth ◽  
Cluster Data ◽  
Proton Temperature ◽  
Sheet Bending ◽  
Wide Range

Abstract. A specific class of solutions of the Vlasov–Maxwell equations, developed by means of generalization of the well-known Harris–Fadeev–Kan–Manankova family of exact two-dimensional equilibria, is studied. The examined model reproduces the current sheet bending and shifting in the vertical plane, arising from the Earth dipole tilting and the solar wind nonradial propagation. The generalized model allows magnetic configurations with equatorial magnetic fields decreasing in a tailward direction as slow as 1∕x, contrary to the original Kan model (1∕x3); magnetic configurations with a single X point are also available. The analytical solution is compared with the empirical T96 model in terms of the magnetic flux tube volume. It is found that parameters of the analytical model may be adjusted to fit a wide range of averaged magnetotail configurations. The best agreement between analytical and empirical models is obtained for the midtail at distances beyond 10–15 RE at high levels of magnetospheric activity. The essential model parameters (current sheet scale, current density) are compared to Cluster data of magnetotail crossings. The best match of parameters is found for single-peaked current sheets with medium values of number density, proton temperature and drift velocity.

scholarly journals Dynamics of variable dusk–dawn flow associated with magnetotail current sheet flapping

2021 ◽  
Vol 39 (6) ◽  
pp. 1037-1053
Author(s):  
James H. Lane ◽  
Adrian Grocott ◽  
Nathan A. Case ◽  
Maria-Theresia Walach
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Large Scale ◽  
Magnetic Field Data ◽  
Analysis Technique ◽  
Upstream Solar Wind ◽  
Magnetotail Dynamics ◽  
Earthward Flow ◽  
The Magnetic Field ◽  
Magnetotail Current Sheet

Abstract. We present Cluster spacecraft observations from 12 October 2006 of convective plasma flows in the Earth's magnetotail. Earthward flow bursts with a dawnward v⊥y component, observed by Cluster 1 (C1), are inconsistent with the duskward flow that might be expected at the pre-midnight location of the spacecraft. Previous observations have suggested that the dusk–dawn sense of the flow can be governed by the interplanetary magnetic field (IMF) By conditions, with the related “untwisting hypothesis” of magnetotail dynamics commonly invoked to explain this dependence, in terms of a large-scale magnetospheric asymmetry. In the current study, observations of the upstream solar wind conditions from OMNI, magnetic field observations by Cluster and ionospheric convection data using SuperDARN indicate a large-scale magnetospheric morphology consistent with positive IMF By penetration into the magnetotail. At the pre-midnight location of Cluster, however, the dawnward flow observed below the neutral sheet by C1 could only be explained by the untwisting hypothesis in a negative IMF By scenario. The Cluster magnetic field data also reveal a flapping of the magnetotail current sheet, a phenomenon known to influence dusk–dawn flow. Results from the curlometer analysis technique suggest that the dusk–dawn sense of the J×B force was consistent with localised kinks in the magnetic field and the flapping associated with the transient perturbations to the dusk–dawn flow observed by C1. We therefore suggest that the flapping overcame the dusk–dawn sense of the large-scale convection which we would expect to have been net duskward in this case. We conclude that invocation of the untwisting hypothesis may be inappropriate when interpreting intervals of dynamic magnetotail behaviour such as during current sheet flapping, particularly at locations where magnetotail flaring becomes dominant.

MMS-Cluster conjugate observation of disturbance in the current sheet associated with localized fast flow in the near-Earth magnetotail

2020 ◽  
Author(s):  
Rumi Nakamura ◽  
Wolfgang Baumjohann ◽  
Joachim Birn ◽  
Jim Burch ◽  
Chris Carr ◽  
...  
Keyword(s):  
Current Sheet ◽  
Equatorial Region ◽  
Small Scale ◽  
Dipolarization Front ◽  
Magnetospheric Multiscale ◽  
Statistical Studies ◽  
Point Data ◽  
Fast Flow ◽  
Magnetotail Dynamics

&lt;p&gt;We report the evolution of the current sheet associated with a localized flow burst in the near-Earth magnetotail on Sep. 8, 2018 around 14 UT when MMS (Magnetospheric Multiscale) and Cluster at about X=17 RE, separated mainly in the dawn-dusk direction at a distance of about 4 RE, encountered at duskside and dawnside part of a dipolarization front, respectively.&amp;#160; We analyzed the mesoscale current sheet disturbances based on multi-point data analysis between Cluster and MMS. It is shown that the current sheet thickens associated with the passage of the dipolarization front confirming results from previous statistical studies. The thickness of the current sheet, however, decreased subsequently, before recovering toward the original configuration. MMS observed enhanced field aligned currents exclusively during this thinning of the current sheet at the off-equatorial region. Multiple layers of small-scale, intense field-aligned currents accompanied by enhanced Hall-currents were detected at this region.&amp;#160; Based on these mesoscale and microscale multipoint observations, we infer the current structures around the localized flow and discuss the role of these mesoscale flow processes in the larger-scale magnetotail dynamics.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

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

Observational support for the current sheet catastrophe model of substorm current disruption

1992 ◽  
Vol 19 (16) ◽  
pp. 1635-1638 ◽  
Author(s):  
G. R. Burkhart ◽  
R. E. Lopez ◽  
P. B. Dusenbery ◽  
T. W. Speiser
Keyword(s):  
Current Sheet ◽  
Catastrophe Model ◽  
Current Disruption

scholarly journals Solar wind and substorm excitation of the wavy current sheet

2009 ◽  
Vol 27 (6) ◽  
pp. 2457-2474 ◽  
Author(s):  
C. Forsyth ◽  
M. Lester ◽  
R. C. Fear ◽  
E. Lucek ◽  
I. Dandouras ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Current Sheet ◽  
Pressure Pulse ◽  
Wind Pressure ◽  
Expansion Velocity ◽  
Solar Wind Pressure ◽  
Wave Models ◽  
Best Fit ◽  
The Magnetic Field

Abstract. Following a solar wind pressure pulse on 3 August 2001, GOES 8, GOES 10, Cluster and Polar observed dipolarizations of the magnetic field, accompanied by an eastward expansion of the aurora observed by IMAGE, indicating the occurrence of two substorms. Prior to the first substorm, the motion of the plasma sheet with respect to Cluster was in the ZGSM direction. Observations following the substorms show the occurrence of current sheet waves moving predominantly in the −YGSM direction. Following the second substorm, the current sheet waves caused multiple current sheet crossings of the Cluster spacecraft, previously studied by Zhang et al. (2002). We further this study to show that the velocity of the current sheet waves was similar to the expansion velocity of the substorm aurora and the expansion of the dipolarization regions in the magnetotail. Furthermore, we compare these results with the current sheet wave models of Golovchanskaya and Maltsev (2005) and Erkaev et al. (2008). We find that the Erkaev et al. (2008) model gives the best fit to the observations.

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