Observations of Closed Magnetic Flux Embedded in the Lobes During Periods of Northward IMF

Fryer, L. J., Fear, R. C., Coxon, John 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, 126 (6). e2021JA029281. ISSN 2169-9380

JGR Space Physics - 2021 - Fryer - Observations of Closed Magnetic Flux Embedded in the Lobes During Periods of Northward.pdf - Published Version
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Official URL: https://doi.org/10.1029/2021JA029281


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.

Item Type: Article
Additional Information: Funding information: LJF was supported by the UK's Science and Technology Facilities Council (STFC) through studentship ST/T506424/1 (2279917). RCF and JCC were supported by STFC Consolidated Grant ST/R000719/1. ILG was support-ed by Royal Society University Research Fellowship URF/R1/191547.
Subjects: H100 General Engineering
H900 Others in Engineering
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Rachel Branson
Date Deposited: 07 Jan 2022 11:33
Last Modified: 07 Jan 2022 11:45
URI: http://nrl.northumbria.ac.uk/id/eprint/48095

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