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A sequence of flux transfer events potentially generated by different generation mechanisms

A sequence of flux transfer events potentially generated by different generation mechanisms
A sequence of flux transfer events potentially generated by different generation mechanisms
Flux transfer events (FTEs) are magnetic structures generated by time-varying reconnection at the dayside magnetopause. Understanding their generation mechanism is important, because it is necessary in order to understand the global contribution of FTEs to the convection process. We present observations of several FTEs sequentially observed by Cluster at the subsolar magnetopause. Cluster detected also several reconnection jets, which seem to be systematically associated with the trailing edge of the FTEs. This association is expected only in the FTEs formed by single X line reconnection but could be compatible also with the multiple X line model, when reconnection at one X line is dominant. Instead, it does not seem compatible with original mechanism proposed by Russell and Elphic (1978). For a large FTE, not associated with any reconnection jet, the Grad-Shafranov reconstruction obtained from Cluster 1 data recovers a flux rope, indicative of multiple X line reconnection. This same FTE was detected also by Cluster 3, which observed an asymmetric signature in the magnetic field component normal to the magnetopause. We show that this asymmetric signature was caused by an outward motion of the magnetopause. The orientation of the other FTEs, obtained from a Grad-Shafranov optimization, shows considerable spread, despite the relatively steady conditions. Our interpretation is that a combination of single and multiple X line reconnection generated these FTEs. The FTEs in the first part of the crossing, associated with reconnection jets, are generated by the single X line model and may therefore not satisfy the Grad-Shafranov assumptions so well. Instead, the last FTE, slower, bigger, and well separated from the previous ones, may be formed by multiple X line reconnection.
2169-9380
8624-8639
Trenchi, L.
565a6c2f-9b87-4a3a-a453-ff7cfecbb266
Fear, R. C.
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Trattner, K. J.
16c79a6f-f7b9-4be8-bf69-b64445a72f2c
Mihaljcic, B.
28c7c33a-7e97-4108-a60c-531d9fa1f5db
Fazakerley, A. N.
9439164e-a929-4946-980a-57100ac43ec6
Trenchi, L.
565a6c2f-9b87-4a3a-a453-ff7cfecbb266
Fear, R. C.
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Trattner, K. J.
16c79a6f-f7b9-4be8-bf69-b64445a72f2c
Mihaljcic, B.
28c7c33a-7e97-4108-a60c-531d9fa1f5db
Fazakerley, A. N.
9439164e-a929-4946-980a-57100ac43ec6

Trenchi, L., Fear, R. C., Trattner, K. J., Mihaljcic, B. and Fazakerley, A. N. (2016) A sequence of flux transfer events potentially generated by different generation mechanisms Journal of Geophysical Research: Space Physics, 121, (9), pp. 8624-8639.

Record type: Article

Abstract

Flux transfer events (FTEs) are magnetic structures generated by time-varying reconnection at the dayside magnetopause. Understanding their generation mechanism is important, because it is necessary in order to understand the global contribution of FTEs to the convection process. We present observations of several FTEs sequentially observed by Cluster at the subsolar magnetopause. Cluster detected also several reconnection jets, which seem to be systematically associated with the trailing edge of the FTEs. This association is expected only in the FTEs formed by single X line reconnection but could be compatible also with the multiple X line model, when reconnection at one X line is dominant. Instead, it does not seem compatible with original mechanism proposed by Russell and Elphic (1978). For a large FTE, not associated with any reconnection jet, the Grad-Shafranov reconstruction obtained from Cluster 1 data recovers a flux rope, indicative of multiple X line reconnection. This same FTE was detected also by Cluster 3, which observed an asymmetric signature in the magnetic field component normal to the magnetopause. We show that this asymmetric signature was caused by an outward motion of the magnetopause. The orientation of the other FTEs, obtained from a Grad-Shafranov optimization, shows considerable spread, despite the relatively steady conditions. Our interpretation is that a combination of single and multiple X line reconnection generated these FTEs. The FTEs in the first part of the crossing, associated with reconnection jets, are generated by the single X line model and may therefore not satisfy the Grad-Shafranov assumptions so well. Instead, the last FTE, slower, bigger, and well separated from the previous ones, may be formed by multiple X line reconnection.

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Accepted/In Press date: 18 August 2016
e-pub ahead of print date: 23 September 2016
Published date: September 2016
Organisations: Astronomy Group

Identifiers

Local EPrints ID: 404298
URI: http://eprints.soton.ac.uk/id/eprint/404298
ISSN: 2169-9380
PURE UUID: 8c84533b-c4ef-4d31-a34c-ff484e0ffa73
ORCID for R. C. Fear: ORCID iD orcid.org/0000-0003-0589-7147

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Date deposited: 05 Jan 2017 14:05
Last modified: 15 Oct 2017 23:06

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Contributors

Author: L. Trenchi
Author: R. C. Fear ORCID iD
Author: K. J. Trattner
Author: B. Mihaljcic
Author: A. N. Fazakerley

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