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Direct observation of closed magnetic flux trapped in the high-latitude magnetosphere

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journal contribution
posted on 28.02.2019, 11:43 by RC Fear, SE Milan, R Maggiolo, AN Fazakerley, I Dandouras, SB Mende
The structure of Earth's magnetosphere is poorly understood when the interplanetary magnetic field is northward. Under this condition, uncharacteristically energetic plasma is observed in the magnetotail lobes, which is not expected in the textbook model of the magnetosphere. Using satellite observations, we show that these lobe plasma signatures occur on high-latitude magnetic field lines that have been closed by the fundamental plasma process of magnetic reconnection. Previously, it has been suggested that closed flux can become trapped in the lobe and that this plasma-trapping process could explain another poorly understood phenomenon: the presence of auroras at extremely high latitudes, called transpolar arcs. Observations of the aurora at the same time as the lobe plasma signatures reveal the presence of a transpolar arc. The excellent correspondence between the transpolar arc and the trapped closed flux at high altitudes provides very strong evidence of the trapping mechanism as the cause of transpolar arcs.

Funding

Work in the UK was supported by Science and Technology Facilities Council (STFC) Ernest Rutherford Fellowship ST/K004298/1 and STFC grants ST/K001000/1 and ST/K000977/1. R.M. is supported by the Belgian Science Policy Office through the Solar-Terrestrial Center of Excellence. French participation in the Cluster project is funded by the Centre National d’Etudes Spatiales (CNES). IMAGE satellite work at the University of California, Berkeley, was supported through a Southwest Research Institute subcontract under NASA contract NAS5-96020.

History

Citation

Science, 2014, 346 (6216), pp. 1506-1510

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

AM (Accepted Manuscript)

Published in

Science

Publisher

American Association for the Advancement of Science

eissn

1095-9203

Copyright date

2014

Available date

28/02/2019

Publisher version

http://science.sciencemag.org/content/346/6216/1506

Language

en

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