Yao, ZH;
Pu, ZY;
Owen, CJ;
Fu, SY;
Chu, XN;
Liu, J;
Angelopoulos, V;
... Du, AM; + view all
(2014)
Current reduction in a pseudo-breakup event: THEMIS observations.
Journal of Geophysical Research: Space Physics
, 119
(10)
pp. 8178-8187.
10.1002/2014JA020186.
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Abstract
Pseudo-breakup events are thought to be generated by the same physical processes as substorms. This paper reports on the cross-tail current reduction in an isolated pseudo-breakup observed by three of the THEMIS probes (THEMIS A (THA), THEMIS D (THD), and THEMIS E (THE)) on 22 March 2010. During this pseudo-breakup, several localized auroral intensifications were seen by ground-based observatories. Using the unique spatial configuration of the three THEMIS probes, we have estimated the inertial and diamagnetic currents in the near-Earth plasma sheet associated with flow braking and diversion. We found the diamagnetic current to be the major contributor to the current reduction in this pseudo-breakup event. During flow braking, the plasma pressure was reinforced, and a weak electrojet and an auroral intensification appeared. After flow braking/diversion, the electrojet was enhanced, and a new auroral intensification was seen. The peak current intensity of the electrojet estimated from ground-based magnetometers, ~0.7 × 105 A, was about 1 order of magnitude lower than that in a typical substorm. We suggest that this pseudo-breakup event involved two dynamical processes: a current-reduction associated with plasma compression ahead of the earthward flow and a current-disruption related to the flow braking/diversion. Both processes are closely connected to the fundamental interaction between fast flows, the near-Earth ambient plasma, and the magnetic field.
| Type: | Article |
|---|---|
| Title: | Current reduction in a pseudo-breakup event: THEMIS observations |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1002/2014JA020186 |
| Publisher version: | http://dx.doi.org/10.1002/2014JA020186 |
| Language: | English |
| Additional information: | Copyright © 2014 The Authors. This is an open access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
| Keywords: | science & technology, physical sciences, astronomy & astrophysics, field-aligned currents, fast flow, current disruption, substorm, pressure gradient, dipolarization front, substorm current wedge, current disruption, mhd simulations, current sheet, growth-phase, flow bursts, plasma-flow, braking, tail, dipolarization |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1449216 |
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