Correlation of core field polarity of magnetotail flux ropes with the IMF By: Reconnection guide field dependency

Teh Wai Leong, R. Nakamura, H. Karimabadi, W. Baumjohann, T. L. Zhang

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The relationship between the core field and the interplanetary magnetic field (IMF) By has been addressed by spacecraft observations in the magnetotail, but it is not yet fully clear since observations by Slavin et al. (2003) and Borg et al. (2012) show controversial results. In this study, we examine 13 flux ropes from the Cluster observations to show for the first time that the correlation between the core field Bcore and the IMF B y depends on the guide field Bg. For large guide fields (> 20% of the reconnecting field), we show that the Bcore is found to correlate with the IMF By. However, for weak guide fields (<10% of the reconnecting field) we show that the core fields have either a positive or negative polarity, irrespective of the IMF By. This result indicates that for weak guide field reconnection the core field generation of the magnetotail flux rope is not governed by the external IMF By. We can explain the previous controversy in terms of the guide field dependency. We also confirm earlier suggestions that for weak guide field reconnection the flux ropes can have a significant core field whose polarity agrees with the ambient quadrupole Hall field. In addition, the Grad-Shafranov reconstruction results suggest that the axis of the flux rope may have been kinked. Our findings are crucial and can help advance theoretical simulations of the core field generation for weak guide reconnection. Discussions of the possible core field generation for weak guide field will be given in terms of 3-D reconnection. Key Points Correlation between core field and IMF By is guide field dependent Reconnection guide field dependency can explain previous controversial results Results are crucial to studying core field generation for weak guide field

Original languageEnglish
Pages (from-to)2933-2944
Number of pages12
JournalJournal of Geophysical Research: Space Physics
Volume119
Issue number4
DOIs
Publication statusPublished - 2014

Fingerprint

Cable cores
magnetotails
ropes
magnetotail
interplanetary magnetic fields
magnetic fields
polarity
Magnetic fields
Fluxes
magnetic field
Spacecraft
spacecraft
suggestion
quadrupoles
simulation

Keywords

  • Interplanetary Magnetic Field
  • Magnetic Flux Rope
  • Magnetic Reconnection
  • Magnetotail

ASJC Scopus subject areas

  • Space and Planetary Science
  • Geophysics

Cite this

Correlation of core field polarity of magnetotail flux ropes with the IMF By : Reconnection guide field dependency. / Wai Leong, Teh; Nakamura, R.; Karimabadi, H.; Baumjohann, W.; Zhang, T. L.

In: Journal of Geophysical Research: Space Physics, Vol. 119, No. 4, 2014, p. 2933-2944.

Research output: Contribution to journalArticle

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