22 Oct 2021

22 Oct 2021

Review status: this preprint is currently under review for the journal ANGEO.

Dayside magnetopause reconnection and flux transfer events: BepiColombo earth-Flyby observations

Weijie Sun1, James A. Slavin1, Rumi Nakamura2, Daniel Heyner3, Karlheinz J. Trattner4, Johannes Z. D. Mieth3, Jiutong Zhao5, Qiu-Gang Zong5, Sae Aizawa6,7, Nicolas Andre6, and Yoshifumi Saito8 Weijie Sun et al.
  • 1Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109, United States
  • 2Space Research Institute, Austrian Academy of Sciences, Schmiedlstraße 6, 8042 Graz, Austria
  • 3Institut für Geophysik und extraterrestrische Physik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
  • 4Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA
  • 5School of Earth and Space Sciences, Peking University, Beijing 100871, China
  • 6Institut de Recherche en Astrophysique et Planétologie, CNRS-UPS-CNES, Toulouse, France
  • 7Department of Geophysics, Graduate School of Science, Tohoku University, Sendai, Japan
  • 8Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science, Kanagawa, Japan

Abstract. This study analyzes the flux transfer event (FTE)-type flux ropes and magnetic reconnection around the dayside magnetopause during BepiColombo’s Earth flyby. The magnetosheath corresponds to a high plasma β (~ 8) and the IMF has a significant radial component. Six flux ropes are identified. The motion of flux rope together with the maximum magnetic shear model suggests that the reconnection X-line swipes BepiColombo near the magnetic equator due to an increase of the radial IMF. The flux rope with the highest flux content contains a clear coalescence signature, i.e., two smaller flux ropes merging, supporting theoretical predictions the flux content of flux ropes can grow through coalescence. The secondary reconnection associated with coalescence exhibits a large normalized guide field and a reconnection rate comparable to the reconnection rate measured at the magnetopause (~ 0.1).

Weijie Sun et al.

Status: open (until 15 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on angeo-2021-58', Anonymous Referee #1, 23 Nov 2021 reply

Weijie Sun et al.


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Short summary
This paper presents observations of FTE-type flux ropes on the dayside during BepiColombo's Earth flyby FTE-type flux ropes are a well-known feature of magnetic reconnection on the magnetopause and they can be used to constrain the location of reconnection X-lines. Our study suggests that the magnetopause X-line crossed over BepiColombo from the north as it traversed the magnetopause. Moreover, it also strongly supports that coalescence can create larger flux ropes by combining smaller ones.