EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Ion Scale Flux Rope Observed at the Trailing Edge of the Hot Flow Anomaly

Shi-Chen Bai1,2, Quanqi Shi1, Terry Liu3,4,5, Hui Zhang5, Chao Yue2,6, Wei-Jie Sun7, Anmin Tian1, Alexander Degeling1, Jacob Bortnik2, Jonathan Rae8, and Mengmeng Wang1
Shi-Chen Bai et al.
  • 1Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Shandong University, Weihai, China.
  • 2Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, CA, USA.
  • 3University Corporation for Atmospheric Research, Boulder, CO, USA
  • 4Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California
  • 5Geophysical Institute, University of Alaska Fairbanks, Alaska, USA
  • 6Institute of Space Physics and Applied Technology, Peking University, Beijing, China
  • 7Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA
  • 8Mullard Space Science Laboratory, Space and Climate Physics, University College London, Dorking, UK

  Magnetic reconnection occurring during the development of a Hot flow anomaly (HFA) has been generated in hybrid simulation, but has never been observed by spacecraft. Using MMS we report an ion scale flux rope like structure, which is Earthward moving, embedded within the trailing edge of a hot flow anomaly (HFA) upstream from the quasi-parallel bow shock. The driver discontinuity of the HFA, a tangential discontinuity, is observed in the solar wind, but no flux rope signatures are observed around it. This suggests that the earthward moving flux rope was generated inside the HFA. This flux rope is close to a one-dimensional structure and expands due to a strong magnetic pressure gradient force. Solar wind ions are decelerated inside the flux rope by the static electric field likely caused by the charge separation of solar wind particles. Our observations imply that magnetic reconnection may have occurred inside the HFA. Reconnection and flux ropes may play a role in particle acceleration/heating inside foreshock transients.

How to cite: Bai, S.-C., Shi, Q., Liu, T., Zhang, H., Yue, C., Sun, W.-J., Tian, A., Degeling, A., Bortnik, J., Rae, J., and Wang, M.: Ion Scale Flux Rope Observed at the Trailing Edge of the Hot Flow Anomaly, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6535,, 2020


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