scholarly journals Large-amplitude electric fields associated with bursty bulk flow braking in the Earth's plasma sheet

2015 ◽  
Vol 120 (3) ◽  
pp. 1832-1844 ◽  
Author(s):  
R. E. Ergun ◽  
K. A. Goodrich ◽  
J. E. Stawarz ◽  
L. Andersson ◽  
V. Angelopoulos

2010 ◽  
Vol 115 (A5) ◽  
pp. n/a-n/a ◽  
Author(s):  
E. V. Panov ◽  
R. Nakamura ◽  
W. Baumjohann ◽  
V. A. Sergeev ◽  
A. A. Petrukovich ◽  
...  


2004 ◽  
Vol 22 (4) ◽  
pp. 1061-1075 ◽  
Author(s):  
A. Grocott ◽  
T. K. Yeoman ◽  
R. Nakamura ◽  
S. W. H. Cowley ◽  
H. U. Frey ◽  
...  

Abstract. On 07 September 2001 the Cluster spacecraft observed a "bursty bulk flow" event in the near-Earth central plasma sheet. This paper presents a detailed study of the coincident ground-based observations and attempts to place them within a simple physical framework. The event in question occurs at ~22:30 UT, some 10min after a southward turning of the IMF. IMAGE and SAMNET magnetometer measurements of the ground magnetic field reveal perturbations of a few tens of nT and small amplitude Pi2 pulsations. CUTLASS radar observations of ionospheric plasma convection show enhanced flows out of the polar cap near midnight, accompanied by an elevated transpolar voltage. Optical data from the IMAGE satellite also show that there is a transient, localised ~1 kR brightening in the UV aurora. These observations are consistent with the earthward transport of plasma in the tail, but also indicate the absence of a typical "large-scale" substorm current wedge. An analysis of the field-aligned current system implied by the radar measurements does suggest the existence of a small-scale current "wedgelet", but one which lacks the global scale and high conductivities observed during substorm expansions. Key words. Ionosphere (auroral ionosphere; ionospheremagnetosphere interactions; plasma convection)



2006 ◽  
Vol 122 (1-4) ◽  
pp. 301-311 ◽  
Author(s):  
Z. Vörös ◽  
W. Baumjohann ◽  
R. Nakamura ◽  
M. Volwerk ◽  
A. Runov


2016 ◽  
Vol 43 (5) ◽  
pp. 1854-1861 ◽  
Author(s):  
Tieyan Wang ◽  
Jinbin Cao ◽  
Huishan Fu ◽  
Xuejie Meng ◽  
M. Dunlop


2007 ◽  
Vol 14 (4) ◽  
pp. 535-541 ◽  
Author(s):  
Z. Vörös ◽  
W. Baumjohann ◽  
R. Nakamura ◽  
A. Runov ◽  
M. Volwerk ◽  
...  

Abstract. Bursty bulk flow associated magnetic fluctuations exhibit at least three spectral scaling ranges in the Earth's plasma sheet. Two of the three scaling ranges can be associated with multi-scale magnetohydrodynamic turbulence between the spatial scales from ~100 km to several RE (RE is the Earth's radius). These scales include the inertial range and below ~0.5 RE a steepened scaling range, theoretically not fully understood yet. It is shown that, in the near-Earth plasma sheet, the inertial range can be robustly identified only if multi-scale quasi stationary (MSQS) data intervals are selected. Multiple bursty flow associated magnetic fluctuations, however, exhibit 1/f type scaling indicating that large-scale fluctuations are controlled by multiple uncorrelated driving sources of the bulk flows (e.g. magnetic reconnection, instabilities).



2001 ◽  
Vol 19 (9) ◽  
pp. 1089-1094 ◽  
Author(s):  
A. Korth ◽  
Z. Y. Pu

Abstract. In this paper, we present an interpretation of the observed field-aligned acceleration events measured by GEOS-2 near the night-side synchronous orbit at substorm onsets (Chen et al., 2000). We show that field-aligned acceleration of ions (with pitch angle asymmetry) is closely related to strong short-lived electric fields in the Ey direction. The acceleration is associated with either rapid dipolarization or further stretching of local magnetic field lines. Theoretical analysis suggests that a centrifugal mechanism is a likely candidate for the parallel energization. Equatorward or anti-equatorward energization occurs when the tail current sheet is thinner tailward or earthward of the spacecraft, respectively. The magnetic field topology leading to anti-equatorward energization corresponds to a situation where the near-Earth tail undergoes further compression and the inner edge of the plasma sheet extends inwards as close as the night-side geosynchronous altitudes.Key words. Magnetospheric physics (magnetospheric configuration and dynamics; plasma sheet; storms and sub-storms)



2008 ◽  
Vol 26 (6) ◽  
pp. 1617-1639 ◽  
Author(s):  
D. V. Sarafopoulos

Abstract. We suggest a candidate physical mechanism, combining there dimensional structure and temporal development, which is potentially able to produce suprathermal populations and cross-tail current disruptions in the Earth's plasma sheet. At the core of the proposed process is the "akis" structure; in a thin current sheet (TCS) the stretched (tail-like) magnetic field lines locally terminate into a sharp tip around the tail midplane. At this sharp tip of the TCS, ions become non-adiabatic, while a percentage of electrons are accumulated and trapped: The strong and transient electrostatic electric fields established along the magnetic field lines produce suprathermal populations. In parallel, the tip structure is associated with field aligned and mutually attracted parallel filamentary currents which progressively become more intense and inevitably the structure collapses, and so does the local TCS. The mechanism is observationally based on elementary, almost autonomous and spatiotemporal entities that correspond each to a local thinning/dipolarization pair having duration of ~1 min. Energetic proton and electron populations do not occur simultaneously, and we infer that they are separately accelerated at local thinnings and dipolarizations, respectively. In one example energetic particles are accelerated without any dB/dt variation and before the substorm expansion phase onset. A particular effort is undertaken demonstrating that the proposed acceleration mechanism may explain the plasma sheet ratio Ti/Te≈7. All our inferences are checked by the highest resolution datasets obtained by the Geotail Energetic Particles and Ion Composition (EPIC) instrument. The energetic particles are used as the best diagnostics for the accelerating source. Near Earth (X≈10 RE) selected events support our basic concept. The proposed mechanism seems to reveal a fundamental building block of the substorm phenomenon and may be the basic process/structure, which is now missing, that might help explain the persistent, outstanding deficiencies in our physical description of magnetospheric substorms. The mechanism is tested, checked, and found consistent with substorm associated observations performed ~30 and 60 RE away from Earth.



2005 ◽  
Vol 48 (2) ◽  
pp. 277-283 ◽  
Author(s):  
Yu-Duan MA ◽  
Jin-Bin CAO ◽  
Guo-Cheng ZHOU ◽  
Zhen-Xin LIU ◽  
H. Reme ◽  
...  


2019 ◽  
Vol 872 (2) ◽  
pp. L26 ◽  
Author(s):  
M. Zhou ◽  
J. Huang ◽  
H. Y. Man ◽  
X. H. Deng ◽  
Z. H. Zhong ◽  
...  


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