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Observations of closed magnetic flux embedded in the lobes during periods of northward IMF

Observations of closed magnetic flux embedded in the lobes during periods of northward IMF
Observations of closed magnetic flux embedded in the lobes during periods of northward IMF
The high latitude, lobe regions of the magnetosphere are often assumed to contain cool, low energy plasma populations. However, during periods of northward Interplanetary Magnetic Field, energetic plasma populations have occasionally been observed. We present three cases when Cluster observed uncharacteristically “hot” plasma populations in the lobe. For two of the three events, we present simultaneous observations of the plasma sheet observed by Double Star. The similarity between the plasma in the lobe and the plasma sheet suggests that the mechanism that produces plasma at high latitudes is likely to be tail reconnection, resulting in a trapped “wedge” of closed flux about the noon-midnight meridian. Complementary images from Imager for Magnetopause to Aurora Global Exploration and DMSP/Special Sensor Ultraviolet Spectrographic Imager show that transpolar arcs, which form in each event in at least one hemisphere, directly intersect the footprint of the Cluster spacecraft in all three events. The intersection of the Cluster footprint with the transpolar arcs is synchronous with the observation of the energetic plasma populations in the lobe. This further supports the conclusion that it is likely this energetic plasma observed in the high latitude lobe regions of magnetosphere is on closed field lines.
2169-9380
Fryer, L. J.
6a9fd678-d71b-4352-a74f-51fa0bdc4542
Fear, R. C.
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Coxon, J. C.
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Gingell, I. L.
ba7b8113-3833-40d8-a879-aab3f987455d
Fryer, L. J.
6a9fd678-d71b-4352-a74f-51fa0bdc4542
Fear, R. C.
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Coxon, J. C.
566baea5-6a30-4855-bde3-a09c115efde4
Gingell, I. L.
ba7b8113-3833-40d8-a879-aab3f987455d

Fryer, L. J., Fear, R. C., Coxon, J. C. and Gingell, I. L. (2021) Observations of closed magnetic flux embedded in the lobes during periods of northward IMF. Journal of Geophysical Research: Space Physics. (doi:10.1029/2021JA029281).

Record type: Article

Abstract

The high latitude, lobe regions of the magnetosphere are often assumed to contain cool, low energy plasma populations. However, during periods of northward Interplanetary Magnetic Field, energetic plasma populations have occasionally been observed. We present three cases when Cluster observed uncharacteristically “hot” plasma populations in the lobe. For two of the three events, we present simultaneous observations of the plasma sheet observed by Double Star. The similarity between the plasma in the lobe and the plasma sheet suggests that the mechanism that produces plasma at high latitudes is likely to be tail reconnection, resulting in a trapped “wedge” of closed flux about the noon-midnight meridian. Complementary images from Imager for Magnetopause to Aurora Global Exploration and DMSP/Special Sensor Ultraviolet Spectrographic Imager show that transpolar arcs, which form in each event in at least one hemisphere, directly intersect the footprint of the Cluster spacecraft in all three events. The intersection of the Cluster footprint with the transpolar arcs is synchronous with the observation of the energetic plasma populations in the lobe. This further supports the conclusion that it is likely this energetic plasma observed in the high latitude lobe regions of magnetosphere is on closed field lines.

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2021JA029281 - Version of Record
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Accepted/In Press date: 12 May 2021
e-pub ahead of print date: 18 June 2021

Identifiers

Local EPrints ID: 450231
URI: http://eprints.soton.ac.uk/id/eprint/450231
ISSN: 2169-9380
PURE UUID: 513a4120-33c7-4902-8003-cf87be487255
ORCID for R. C. Fear: ORCID iD orcid.org/0000-0003-0589-7147
ORCID for J. C. Coxon: ORCID iD orcid.org/0000-0002-0166-6854

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Date deposited: 16 Jul 2021 16:35
Last modified: 17 Jul 2021 01:50

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Contributors

Author: L. J. Fryer
Author: R. C. Fear ORCID iD
Author: J. C. Coxon ORCID iD
Author: I. L. Gingell

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