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    Rights statement: An edited version of this paper was published by AGU. Copyright 2019 American Geophysical Union. Sandhu, J. K., Rae, I. J., Freeman, M. P., Gkioulidou, M., Forsyth, C., Reeves, G. D., et al. ( 2019). Substorm‐ring current coupling: A comparison of isolated and compound substorms. Journal of Geophysical Research: Space Physics, 124. https://doi.org/10.1029/2019JA026766. To view the published open abstract, go to http://dx.doi.org and enter the DOI.

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    Available under license: CC BY-NC: Creative Commons Attribution-NonCommercial 4.0 International License

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Substorm‐Ring Current Coupling: A Comparison of Isolated and Compound Substorms

Research output: Contribution to journalJournal article

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  • J. K. Sandhu
  • I.J. Rae
  • M.P. Freeman
  • M. Gkioulidou
  • C. Forsyth
  • G. D. Reeves
  • K. R. Murphy
  • Maria Walach
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<mark>Journal publication date</mark>31/08/2019
<mark>Journal</mark>Journal of Geophysical Research: Space Physics
Issue number8
Volume124
Number of pages16
Pages (from-to)6776-6791
Publication StatusPublished
Early online date17/08/19
<mark>Original language</mark>English

Abstract

Substorms are a highly variable process, which can occur as an isolated event or as part of a sequence of multiple substorms (compound substorms). In this study we identify how the low‐energy population of the ring current and subsequent energization varies for isolated substorms compared to the first substorm of a compound event. Using observations of H+ and O+ ions (1 eV to 50 keV) from the Helium Oxygen Proton Electron instrument onboard Van Allen Probe A, we determine the energy content of the ring current in L‐MLT space. We observe that the ring current energy content is significantly enhanced during compound substorms as compared to isolated substorms by ∼20–30%. Furthermore, we observe a significantly larger magnitude of energization (by ∼40–50%) following the onset of compound substorms relative to isolated substorms. Analysis suggests that the differences predominantly arise due to a sustained enhancement in dayside driving associated with compound substorms compared to isolated substorms. The strong solar wind driving prior to onset results in important differences in the time history of the magnetosphere, generating significantly different ring current conditions and responses to substorms. The observations reveal information about the substorm injected population and the transport of the plasma in the inner magnetosphere.

Bibliographic note

An edited version of this paper was published by AGU. Copyright 2019 American Geophysical Union. Sandhu, J. K., Rae, I. J., Freeman, M. P., Gkioulidou, M., Forsyth, C., Reeves, G. D., et al. ( 2019). Substorm‐ring current coupling: A comparison of isolated and compound substorms. Journal of Geophysical Research: Space Physics, 124. https://doi.org/10.1029/2019JA026766. To view the published open abstract, go to http://dx.doi.org and enter the DOI.