Evidence for the core field polarity of magnetic flux ropes against the reconnection guide field. Issue 11 (13th November 2014)

• Record Type: Journal Article
• Authors: Teh, W.‐L.; Abdullah, M.; Hasbi, A. M.
• Is Part Of: Journal of geophysical research. Volume 119:Issue 11(2014:Nov.)
• Page Start: 8979
• Page End: 8983
• Publication Date: 2014-11-13
• Subjects: Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2014JA020509
• Languages: English
• ISSNs: 2169-9380

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>We present the observational evidence by Time History of Events and Macroscale Interactions during Substorms (THEMIS)‐D spacecraft to demonstrate that magnetic flux rope can have a core field polarity opposite to the guide field during asymmetric reconnection with a high magnetic shear across the magnetopause. In the presented event, a bipolar reconnection outflow was observed at the magnetopause, across which the magnetic shear was ~149° corresponding to a predicted guide field <italic>B</italic>_G = −15.6 nT. The ratios for magnetic field strength and ion density between the magnetospheric and magnetosheath sides of the magnetopause were ~1.6 and ~0.15, respectively. During the event, the component of magnetic field along the <italic>M</italic> axis (the intermediate variance direction) remained negative and stable for most of the time, and its mean value agreed with the <italic>B</italic>_G. Two magnetic flux ropes with a strong core field were identified, but one flux rope had a core field polarity against the guide field <italic>B</italic>_G. Our finding differs from current theoretical simulations that the core field polarity of the flux ropes inherits from the guide field.</p> </abstract>