27 August 2001 substorm: Preonset phenomena, two main onsets, field-aligned current systems, and plasma flow channels in the ionosphere and in the magnetosphere

2017 ◽  
Vol 122 (5) ◽  
pp. 4988-5007 ◽  
Author(s):  
V. M. Mishin ◽  
V. V. Mishin ◽  
S. B. Lunyushkin ◽  
J. Y. Wang ◽  
A. V. Moiseev
Keyword(s):  
Plasma Flow ◽  
Flow Channels ◽  
Field Aligned Current ◽  
Current Systems

Transient cusp ionospheric disturbances caused by a solar wind dynamic pressure enhancement

2021 ◽  
Author(s):  
Jianjun Liu
Keyword(s):  
Plasma Flow ◽  
Dynamic Pressure ◽  
Geomagnetic Disturbance ◽  
Flow Reversal ◽  
Drift Motion ◽  
Zhongshan Station ◽  
Shock Impingement ◽  
Field Aligned Current ◽  
Convection Patterns ◽  
The Antarctic

<p>Interplanetary (IP) shock driven sudden compression produces disturbances in the polar ionosphere. Various studies have investigated the effects of IP shock using imagers and radars. However, very few studies have reported the plasma flow reversal and a sudden vertical plasma drift motion following a CME driven IP shock. We report on the cusp ionospheric features following an IP shock impingement on 16 June 2012, using SuperDARN radar and digisonde from the Antarctic Zhongshan Station (ZHO). SuperDARN ZHO radar observed instant strong plasma flow reversal during the IP shock driven sudden impulse (SI) with a suppression in the number of backscatter echoes. Besides, we also report on a “Doppler Impulse” phenomenon, an instant and brief downward plasma motion, were observed by the digisonde in response to the SI and discuss the possible physical causes. Geomagnetic disturbance and convection patterns indicate the flow reversal was generated by the downward field-aligned current (FAC). We speculate that sudden enhancement in ionization associated with SI is responsible for generating the Doppler Impulse phenomenon.</p>

scholarly journals Plasma flow channels with ULF waves observed by Cluster and Double Star

2005 ◽  
Vol 23 (8) ◽  
pp. 2929-2935 ◽  
Author(s):  
M. Volwerk ◽  
T. L. Zhang ◽  
R. Nakamura ◽  
A. Runov ◽  
W. Baumjohann ◽  
...  
Keyword(s):  
Magnetic Structure ◽  
Plasma Flow ◽  
Large Scale ◽  
Double Star ◽  
Flow Channel ◽  
Propagation Direction ◽  
Ulf Waves ◽  
Flow Channels ◽  
Earthward Flow

Abstract. On 14 August 2004 a large-scale magnetic structure was observed by Double Star TC-1 in the southern lobe and by Cluster in the northern lobe of the magnetotail. The structure has the signature of a (localized) dipolarization, decreasing Bx accompanied by an increasing Bz and a strong earthward flow. The propagation direction of this structure, however, seems to be more in the dawnward direction than earthward. The structure is accompanied by ULF waves with a period of ~5 min, which are simultaneously observed by the ground magnetometer station DIK, at the magnetic footpoints of the spacecraft. We interprete these waves as modes driven by the plasma flow and propagating in the flow channel.

Field-aligned current systems in the magnetospheric ground state

1998 ◽  
Vol 103 (A4) ◽  
pp. 6853-6869 ◽  
Author(s):  
Masakazu Watanabe ◽  
Takesi Iijima ◽  
Masayuki Nakagawa ◽  
Thomas A. Potemra ◽  
Laurence J. Zanetti ◽  
...  
Keyword(s):  
Ground State ◽  
Field Aligned Current ◽  
Current Systems

scholarly journals Plasma flows, Birkeland currents and auroral forms in relation to the Svalgaard-Mansurov effect

2012 ◽  
Vol 30 (5) ◽  
pp. 817-830 ◽  
Author(s):  
P. E. Sandholt ◽  
C. J. Farrugia
Keyword(s):  
Magnetic Field ◽  
Open Field ◽  
Central Element ◽  
Flow Channel ◽  
Plasma Convection ◽  
Polar Cap ◽  
Flow Channels ◽  
Field Lines ◽  
Current Systems ◽  
Birkeland Currents

Abstract. The traditional explanation of the polar cap magnetic deflections, referred to as the Svalgaard-Mansurov effect, is in terms of currents associated with ionospheric flow resulting from the release of magnetic tension on newly open magnetic field lines. In this study, we aim at an updated description of the sources of the Svalgaard-Mansurov effect based on recent observations of configurations of plasma flow channels, Birkeland current systems and aurorae in the magnetosphere-ionosphere system. Central to our description is the distinction between two different flow channels (FC 1 and FC 2) corresponding to two consecutive stages in the evolution of open field lines in Dungey cell convection, with FC 1 on newly open, and FC 2 on old open, field lines. Flow channel FC 1 is the result of ionospheric Pedersen current closure of Birkeland currents flowing along newly open field lines. During intervals of nonzero interplanetary magnetic field By component FC 1 is observed on either side of noon and it is accompanied by poleward moving auroral forms (PMAFs/prenoon and PMAFs/postnoon). In such cases the next convection stage, in the form of flow channel FC 2 on the periphery of the polar cap, is particularly important for establishing an IMF By-related convection asymmetry along the dawn-dusk meridian, which is a central element causing the Svalgaard-Mansurov effect. FC 2 flows are excited by the ionospheric Pedersen current closure of the northernmost pair of Birkeland currents in the four-sheet current system, which is coupled to the tail magnetopause and flank low-latitude boundary layer. This study is based on a review of recent statistical and event studies of central parameters relating to the magnetosphere-ionosphere current systems mentioned above. Temporal-spatial structure in the current systems is obtained by ground-satellite conjunction studies. On this point we emphasize the important information derived from the continuous ground monitoring of the dynamical behaviour of aurora and plasma convection during intervals of well-organised solar wind plasma and magnetic field conditions in interplanetary coronal mass ejections (ICMEs) during their Earth passage.

Altitudinal comparison of dayside field-aligned current signatures by Viking and DMSP-F7: Intermediate-scale field-aligned current systems

1996 ◽  
Vol 101 (A7) ◽  
pp. 15297-15310 ◽  
Author(s):  
S. Ohtani ◽  
L. G. Blomberg ◽  
P. T. Newell ◽  
M. Yamauchi ◽  
T. A. Potemra ◽  
...  
Keyword(s):  
Intermediate Scale ◽  
Scale Field ◽  
Field Aligned Current ◽  
Current Signatures ◽  
Current Systems

scholarly journals A comparison of small‐scale magnetic fluctuations in the Region 1 and 2 field‐aligned current systems

2017 ◽  
Vol 122 (3) ◽  
pp. 3277-3290 ◽  
Author(s):  
J. Wu ◽  
M. S. Bryant ◽  
C. G. Ridley ◽  
Y. Shen ◽  
L. Yang ◽  
...  
Keyword(s):  
Small Scale ◽  
Magnetic Fluctuations ◽  
Field Aligned Current ◽  
Current Systems

scholarly journals THEMIS ground-space observations during the development of auroral spirals

2009 ◽  
Vol 27 (11) ◽  
pp. 4317-4332 ◽  
Author(s):  
A. Keiling ◽  
V. Angelopoulos ◽  
J. M. Weygand ◽  
O. Amm ◽  
E. Spanswick ◽  
...  
Keyword(s):  
Plasma Flow ◽  
Simultaneous Observation ◽  
Model Calculations ◽  
Expansion Phase ◽  
Geocentric Distance ◽  
Field Aligned Current ◽  
Auroral Arcs ◽  
Downward Currents ◽  
A Current ◽  
Space Observations

Abstract. A simultaneous observation of an auroral spiral and its generator region in the near-Earth plasma sheet is rather unlikely. Here we present such observations using the THEMIS spacecraft as well as the THEMIS ground network of all-sky imagers and magnetometers. Two consecutive auroral spirals separated by approximately 14 min occurred during a substorm on 19 February 2008. The spirals formed during the expansion phase and a subsequent intensification, and were among the brightest features in the aurora with diameters of 200–300 km. The duration for the formation and decay of each spiral was less than 60 s. Both spirals occurred shortly after the formation of two oppositely rotating plasma flow vortices in space, which were also accompanied by dipolarizations and ion injections, at ~11 RE geocentric distance. Observations and model calculations also give evidence for a magnetic-field-aligned current generation of approximately 0.1 MA via the flow vortices, connecting the generator region of the spirals with the ionosphere, during the formation of both spirals. In the ionosphere, a pair of equivalent ionospheric current (EIC) vortices with opposite rotations (corresponding to upward and downward currents) was present during both auroral spirals with enhanced EICs and ionospheric flows at the locations of the auroral spirals and along the auroral arcs. The combined ground and space observations suggest that each auroral spiral was powered by two oppositely rotating plasma flow vortices that caused a current enhancement in the substorm current wedge.

scholarly journals Cluster and Double Star multipoint observations of a plasma bubble

2009 ◽  
Vol 27 (2) ◽  
pp. 725-743 ◽  
Author(s):  
A. P. Walsh ◽  
A. N. Fazakerley ◽  
A. D. Lahiff ◽  
M. Volwerk ◽  
A. Grocott ◽  
...  
Keyword(s):  
High Speed ◽  
Double Star ◽  
Plasma Bubble ◽  
Flux Transport ◽  
Flux Tubes ◽  
Plasma Bubbles ◽  
Direct Observations ◽  
Mhd Simulations ◽  
Field Aligned Current ◽  
Current Systems

Abstract. Depleted flux tubes, or plasma bubbles, are one possible explanation of bursty bulk flows, which are transient high speed flows thought to be responsible for a large proportion of flux transport in the magnetotail. Here we report observations of one such plasma bubble, made by the four Cluster spacecraft and Double Star TC-2 around 14:00 UT on 21 September 2005, during a period of southward, but BY-dominated IMF. In particular the first direct observations of return flows around the edges of a plasma bubble, and the first observations of plasma bubble features within 8 RE of the Earth, consistent with MHD simulations (Birn et al., 2004) are presented. The implications of the presence of a strong BY in the IMF and magnetotail on the propagation of the plasma bubble and development of the associated current systems in the magnetotail and ionosphere are discussed. It is suggested that a strong BY can rotate the field aligned current systems at the edges of the plasma bubble away from its duskward and dawnward flanks.

Sign in / Sign up

Export Citation Format

Share Document