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Understanding Spacecraft Trajectories through Detached Magnetotail Interchange Heads
  • Evgeny Panov,
  • San Lu,
  • Philip Pritchett
Evgeny Panov
Space Research Institute, Austrian Academy of Sciences, Graz, Austria

Corresponding Author:evgeny.panov@oeaw.ac.at

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San Lu
Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA, USA
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Philip Pritchett
Department of Physics and Astronomy, University of California, Los Angeles, CA, USA
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The kinetic ballooning/interchange instability (BICI) was recently found to produce azimutally narrow interchange heads extending into the dipole region from a reversed radial gradient of B$_Z$ in the near-Earth magnetotail. In their nonlinear evolution individual heads were predicted to detach from the reversed B$_Z$ gradient and grow into transient earthward moving northward magnetic field intensifications (dipolarization fronts; DFs). The distinguished signatures of such fronts would be their oblique propagation and cross-tail localization due to the finite k$_y$ structure of the BICI modes. Simultaneous conjugate observations of DFs by THEMIS probes at 11 Earth’s radii (R$_E$) downtail and of sudden brightening and growth of individual auroral beads by the all sky imagers on the ground have been suggested to be ionospheric signature of detached magnetotail interchange heads [Panov et al., 2019]. Here we compare such DFs with a simulated interchange head during later(detachment)-stage BICI head development. The comparison reveals similarly structured leading edges and trailing tails in both the observed DFs and the simulated BICI head. We further identify THEMIS trajectories through the DFs and find that the trajectories were due to oblique (earthward and dawnward) DF propagation. This analysis further supports the idea that BICI indeed releases obliquely propagating azimuthally localized dipolarization fronts in the Earth’s magnetotail.
May 2020Published in Journal of Geophysical Research: Space Physics volume 125 issue 5. 10.1029/2020JA027930