Preprints
https://doi.org/10.5194/angeo-2021-32
https://doi.org/10.5194/angeo-2021-32

  03 Jun 2021

03 Jun 2021

Review status: a revised version of this preprint is currently under review for the journal ANGEO.

Dynamics of Variable Dusk-Dawn Flow Associated with Magnetotail Current Sheet Flapping

James Henry Lane, Adrian Grocott, Nathan Anthony Case, and Maria-Theresia Walach James Henry Lane et al.
  • Department of Physics, Lancaster University, Lancaster, UK

Abstract. Previous observations have provided a clear indication that the dusk-dawn (v⊥y) sense of both slow (< 200 km s−1) and fast (> 200 km s−1) convective magnetotail flows is strongly governed by the Interplanetary Magnetic Field (IMF) By conditions. The related “untwisting hypothesis” of magnetotail dynamics is commonly invoked to explain this dependence, in terms of a large-scale magnetospheric asymmetry. In the current study, we present Cluster spacecraft observations from 12 October 2006 of earthward convective magnetotail plasma flows whose dusk-dawn sense disagrees with the untwisting hypothesis of IMF By control of the magnetotail flows. During this interval, observations of the upstream solar wind conditions from OMNI, and ionospheric convection data using SuperDARN, indicate a large-scale magnetospheric morphology consistent with positive IMF By penetration into the magnetotail. Inspection of the in-situ Cluster magnetic field data reveals a flapping of the magnetotail current sheet; a phenomenon known to influence dusk-dawn flow. Results from the curlometer analysis technique suggest that the dusk-dawn flow perturbations may have been driven by the J x B force associated with a dawnward-propagating flapping of the magnetotail current sheet, locally overriding the expected IMF By control of the flows. We conclude that invocation of the untwisting hypothesis may be inappropriate when interpreting intervals of dynamic magnetotail behaviour such as during current sheet flapping.

James Henry Lane et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on angeo-2021-32', Anonymous Referee #1, 01 Jul 2021
    • AC1: 'Reply on RC1', James Lane, 13 Jul 2021
  • RC2: 'Comment on angeo-2021-32', Anonymous Referee #2, 01 Jul 2021
    • AC2: 'Reply on RC2', James Lane, 13 Jul 2021
      • RC3: 'Reply on AC2', Anonymous Referee #2, 15 Jul 2021
        • AC4: 'Reply on RC3', James Lane, 23 Jul 2021
  • RC4: 'Comment on angeo-2021-32', Anonymous Referee #3, 16 Jul 2021
    • AC3: 'Reply on RC4', James Lane, 23 Jul 2021

James Henry Lane et al.

James Henry Lane et al.

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Short summary
The Sun’s magnetic field is carried across space by the solar wind – a hot plasma “stream” of ions and electrons – forming the Interplanetary Magnetic Field (IMF). The IMF can introduce asymmetries into the Earth's magnetic field, giving plasma flowing within it a direction dependent on IMF orientation. Electric currents in near-Earth space can also influence these plasma flows. We investigate these two competing mechanisms and find that the currents can override the IMF control of the flow.