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Small-scale flux transfer events formed in the reconnection exhaust region between two X lines

Small-scale flux transfer events formed in the reconnection exhaust region between two X lines
Small-scale flux transfer events formed in the reconnection exhaust region between two X lines

We report MMS observations of the ion-scale flux transfer events (FTEs) that may involve two main X lines and tearing instability between the two X lines. The four spacecraft detected multiple isolated regions with enhanced magnetic field strength and bipolar Bn signatures normal to the nominal magnetopause, indicating FTEs. The currents within the FTEs flow mostly parallel to B, and the magnetic tension force is balanced by the total pressure gradient force. During these events, the plasma bulk flow velocity was directed southward. Detailed analysis of the magnetic and electric field and plasma moments variations suggests that the FTEs were initially embedded within the exhaust region north of an X line but were later located southward/downstream of a subsequent X line. The cross sections of the individual FTEs are in the range of ~2.5–6.8 ion inertial lengths. The observations suggest the formation of multiple secondary FTEs. The presence of an X line in the exhaust region southward of a second X line results from the southward drift of an old X line and the reformation of a new X line. The current layer between the two X lines is unstable to the tearing instability, generating multiple ion-scale flux-rope-type secondary islands.

flux transfer event, FTE, magnetopause, MMS, reconnection, secondary island
2169-9380
8473-8488
Hwang, K. J.
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Sibeck, D. G.
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Burch, J. L.
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Choi, E.
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Fear, R. C.
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Lavraud, B.
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Giles, B. L.
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Gershman, D.
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Pollock, C. J.
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Eastwood, J. P.
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Khotyaintsev, Y.
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Escoubet, Philippe
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Fu, H.
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Toledo-Redondo, S.
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Torbert, R. B.
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Ergun, R. E.
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Paterson, W. R.
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Dorelli, J. C.
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Avanov, L.
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Russell, C. T.
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Strangeway, R. J.
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Hwang, K. J.
c1ba4bc9-72c0-4af5-9d4a-871deafaf342
Sibeck, D. G.
6004631a-1492-4a41-89dd-5296d8e324d2
Burch, J. L.
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Choi, E.
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Fear, R. C.
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Lavraud, B.
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Giles, B. L.
eceb7be2-b272-40cb-a9af-82687b2708fd
Gershman, D.
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Pollock, C. J.
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Eastwood, J. P.
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Khotyaintsev, Y.
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Escoubet, Philippe
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Fu, H.
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Toledo-Redondo, S.
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Torbert, R. B.
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Ergun, R. E.
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Paterson, W. R.
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Dorelli, J. C.
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Avanov, L.
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Russell, C. T.
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Strangeway, R. J.
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Hwang, K. J., Sibeck, D. G., Burch, J. L., Choi, E., Fear, R. C., Lavraud, B., Giles, B. L., Gershman, D., Pollock, C. J., Eastwood, J. P., Khotyaintsev, Y., Escoubet, Philippe, Fu, H., Toledo-Redondo, S., Torbert, R. B., Ergun, R. E., Paterson, W. R., Dorelli, J. C., Avanov, L., Russell, C. T. and Strangeway, R. J. (2018) Small-scale flux transfer events formed in the reconnection exhaust region between two X lines. Journal of Geophysical Research: Space Physics, 123 (10), 8473-8488. (doi:10.1029/2018JA025611).

Record type: Article

Abstract

We report MMS observations of the ion-scale flux transfer events (FTEs) that may involve two main X lines and tearing instability between the two X lines. The four spacecraft detected multiple isolated regions with enhanced magnetic field strength and bipolar Bn signatures normal to the nominal magnetopause, indicating FTEs. The currents within the FTEs flow mostly parallel to B, and the magnetic tension force is balanced by the total pressure gradient force. During these events, the plasma bulk flow velocity was directed southward. Detailed analysis of the magnetic and electric field and plasma moments variations suggests that the FTEs were initially embedded within the exhaust region north of an X line but were later located southward/downstream of a subsequent X line. The cross sections of the individual FTEs are in the range of ~2.5–6.8 ion inertial lengths. The observations suggest the formation of multiple secondary FTEs. The presence of an X line in the exhaust region southward of a second X line results from the southward drift of an old X line and the reformation of a new X line. The current layer between the two X lines is unstable to the tearing instability, generating multiple ion-scale flux-rope-type secondary islands.

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Accepted/In Press date: 3 October 2018
e-pub ahead of print date: 11 October 2018
Published date: October 2018
Keywords: flux transfer event, FTE, magnetopause, MMS, reconnection, secondary island

Identifiers

Local EPrints ID: 427371
URI: https://eprints.soton.ac.uk/id/eprint/427371
ISSN: 2169-9380
PURE UUID: df292b32-2dfc-4b8e-a216-ca94d379d598
ORCID for R. C. Fear: ORCID iD orcid.org/0000-0003-0589-7147

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Date deposited: 14 Jan 2019 17:30
Last modified: 10 Dec 2019 05:08

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Contributors

Author: K. J. Hwang
Author: D. G. Sibeck
Author: J. L. Burch
Author: E. Choi
Author: R. C. Fear ORCID iD
Author: B. Lavraud
Author: B. L. Giles
Author: D. Gershman
Author: C. J. Pollock
Author: J. P. Eastwood
Author: Y. Khotyaintsev
Author: Philippe Escoubet
Author: H. Fu
Author: S. Toledo-Redondo
Author: R. B. Torbert
Author: R. E. Ergun
Author: W. R. Paterson
Author: J. C. Dorelli
Author: L. Avanov
Author: C. T. Russell
Author: R. J. Strangeway

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