University of Oulu

Chong, G. S., De Spiegeleer, A., Hamrin, M., Pitkänen, T., Gunell, H., & Aizawa, S. (2021). Tailward flows in the vicinity of fast earthward flows. Journal of Geophysical Research: Space Physics, 126, e2020JA028978.

Tailward flows in the vicinity of fast earthward flows

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Author: Chong, Ghai Siung1; De Spiegeleer, A.1; Hamrin, M.1;
Organizations: 1Department of Physics, Umeå University, Umeå, Sweden
2Institute of Space Sciences, Shandong University, Weihai, China
3Space Physics and Astronomy Research Unit, University of Oulu, Oulu, Finland
4Research Institute in Astrophysics and Planetology, Toulouse, France
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 3.2 MB)
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Language: English
Published: American Geophysical Union, 2021
Publish Date: 2021-10-19


The occurrence of tailward flows in the magnetotail plasma sheet is closely linked to the dynamics of earthward bursty bulk flows (BBFs). Tailward flows that are observed in the vicinity of these BBFs (or TWABs – Tailward flows around BBFs) may hold unique information on its origin. In this study, we conduct a statistical survey on TWABs by using data from the Cluster mission. We find that TWABs are observed in the vicinity of ∼75% of the BBFs and their occurrence does not depend on BBF velocity magnitude. TWABs have a flow convection pattern consistent with the general tailward flows (GTWs) in the plasma sheet and they do not resemble vortical-like flows. However, TWABs have a flow velocity magnitude twice larger than the GTWs. The plasma density and temperature of TWABs are comparable with BBFs. It is more common to observe a TWAB succeeding than preceding a BBF. However, there is no distinctive difference (in flow pattern, plasma density and temperature) between preceding and succeeding TWABs. We suggest that TWABs are likely the “freshly” rebounded BBFs from the near-Earth region where the magnetic field is stronger. TWABs may represent the early stage of the evolution of tailward flows in the plasma sheet. We also discuss and argue that other mechanisms such as shear-induced vortical flows and tailward slipping of depleted flux tubes cannot be the principal causes of TWABs.

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Series: Journal of geophysical research. Space physics
ISSN: 2169-9380
ISSN-E: 2169-9402
ISSN-L: 2169-9380
Volume: 126
Issue: 4
Article number: e2020JA028978
DOI: 10.1029/2020JA028978
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: Participants from Umeå University received financial assistance from the Swedish National Space Agency (SNSA) Grant 81/17 and 108/18. T. Pitkänen would like to acknowledge the financial assistance from SNSA Grant 118/17 and from the Natural Science Foundation of China (NSFC) Grant 41750110486.
Copyright information: © 2021. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.