Timescales of Dayside and Nightside Field-Aligned Current Response to Changes in Solar Wind-Magnetosphere Coupling

Stephen E. Milan; Jennifer Alyson Carter; Harneet Sangha; Karl M. Laundal; Nikolai Østgaard; Paul Tenfjord; Jone Peter Reistad; Kristian Snekvik; John C. Coxon; Haje Korth; Brian J. Anderson

doi:10.1029/2018JA025645

Timescales of Dayside and Nightside Field-Aligned Current Response to Changes in Solar Wind-Magnetosphere Coupling

Stephen E. Milan^*, Jennifer Alyson Carter, Harneet Sangha, Karl M. Laundal, Nikolai Østgaard, Paul Tenfjord, Jone Peter Reistad, Kristian Snekvik, John C. Coxon, Haje Korth, Brian J. Anderson

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

Principal component analysis is performed on Birkeland or field-aligned current (FAC) measurements from the Active Magnetosphere and Planetary Electrodynamics Response Experiment, to determine the response of dayside and nightside FACs to reversals in the orientation of the interplanetary magnetic field (IMF) and the occurrence of substorms. Dayside FACs respond promptly to changes in IMF B_Y, but the nightside response is delayed by up to an hour and can take up to 4 hr to develop fully, especially during northward IMF. Nightside FAC asymmetries grow during substorm growth phase when the IMF has a significant B_Y component, and also promptly at substorm onset. Our findings suggest that magnetotail twisting and/or B_Y penetration into the magnetotail, due to subsolar reconnection with east-west orientated IMF, are the main cause of these nightside FAC asymmetries and that asymmetries also arise due to magnetotail reconnection of these twisted field lines.

Original language	English
Pages (from-to)	7307-7319
Number of pages	13
Journal	Journal of Geophysical Research: Space Physics
Volume	123
Issue number	9
Early online date	4 Sept 2018
DOIs	https://doi.org/10.1029/2018JA025645
Publication status	Published - Sept 2018
Externally published	Yes

Keywords

currents
ionosphere
magnetosphere

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10.1029/2018JA025645Licence: CC BY

JGR Space Physics - 2018 - Milan - Timescales of Dayside and Nightside Field‐Aligned Current Response to Changes in SolarFinal published version, 1.78 MBLicence: CC BY

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Milan, S. E., Carter, J. A., Sangha, H., Laundal, K. M., Østgaard, N., Tenfjord, P., Reistad, J. P., Snekvik, K., Coxon, J. C., Korth, H., & Anderson, B. J. (2018). Timescales of Dayside and Nightside Field-Aligned Current Response to Changes in Solar Wind-Magnetosphere Coupling. Journal of Geophysical Research: Space Physics, 123(9), 7307-7319. https://doi.org/10.1029/2018JA025645

@article{609d2a7ea0a3433e9859e615d9e434b7,

title = "Timescales of Dayside and Nightside Field-Aligned Current Response to Changes in Solar Wind-Magnetosphere Coupling",

abstract = "Principal component analysis is performed on Birkeland or field-aligned current (FAC) measurements from the Active Magnetosphere and Planetary Electrodynamics Response Experiment, to determine the response of dayside and nightside FACs to reversals in the orientation of the interplanetary magnetic field (IMF) and the occurrence of substorms. Dayside FACs respond promptly to changes in IMF BY, but the nightside response is delayed by up to an hour and can take up to 4 hr to develop fully, especially during northward IMF. Nightside FAC asymmetries grow during substorm growth phase when the IMF has a significant BY component, and also promptly at substorm onset. Our findings suggest that magnetotail twisting and/or BY penetration into the magnetotail, due to subsolar reconnection with east-west orientated IMF, are the main cause of these nightside FAC asymmetries and that asymmetries also arise due to magnetotail reconnection of these twisted field lines.",

keywords = "currents, ionosphere, magnetosphere",

author = "Milan, {Stephen E.} and Carter, {Jennifer Alyson} and Harneet Sangha and Laundal, {Karl M.} and Nikolai {\O}stgaard and Paul Tenfjord and Reistad, {Jone Peter} and Kristian Snekvik and Coxon, {John C.} and Haje Korth and Anderson, {Brian J.}",

note = "Funding Information: S. E. M. and J. A. C. were supported by the Science and Technology Facilities Council (STFC), UK, grant ST/N000749/1; H. S. was supported by a STFC studentship. The work at the Birkeland Centre for Space Centre, University of Bergen, Norway, was supported by the Research Council of Norway/CoE under contract 223252/F50.",

year = "2018",

month = sep,

doi = "10.1029/2018JA025645",

language = "English",

volume = "123",

pages = "7307--7319",

journal = "Journal of Geophysical Research: Space Physics",

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Milan, SE, Carter, JA, Sangha, H, Laundal, KM, Østgaard, N, Tenfjord, P, Reistad, JP, Snekvik, K, Coxon, JC, Korth, H & Anderson, BJ 2018, 'Timescales of Dayside and Nightside Field-Aligned Current Response to Changes in Solar Wind-Magnetosphere Coupling', Journal of Geophysical Research: Space Physics, vol. 123, no. 9, pp. 7307-7319. https://doi.org/10.1029/2018JA025645

TY - JOUR

T1 - Timescales of Dayside and Nightside Field-Aligned Current Response to Changes in Solar Wind-Magnetosphere Coupling

AU - Milan, Stephen E.

AU - Carter, Jennifer Alyson

AU - Sangha, Harneet

AU - Laundal, Karl M.

AU - Østgaard, Nikolai

AU - Tenfjord, Paul

AU - Reistad, Jone Peter

AU - Snekvik, Kristian

AU - Coxon, John C.

AU - Korth, Haje

AU - Anderson, Brian J.

N1 - Funding Information: S. E. M. and J. A. C. were supported by the Science and Technology Facilities Council (STFC), UK, grant ST/N000749/1; H. S. was supported by a STFC studentship. The work at the Birkeland Centre for Space Centre, University of Bergen, Norway, was supported by the Research Council of Norway/CoE under contract 223252/F50.

PY - 2018/9

Y1 - 2018/9

N2 - Principal component analysis is performed on Birkeland or field-aligned current (FAC) measurements from the Active Magnetosphere and Planetary Electrodynamics Response Experiment, to determine the response of dayside and nightside FACs to reversals in the orientation of the interplanetary magnetic field (IMF) and the occurrence of substorms. Dayside FACs respond promptly to changes in IMF BY, but the nightside response is delayed by up to an hour and can take up to 4 hr to develop fully, especially during northward IMF. Nightside FAC asymmetries grow during substorm growth phase when the IMF has a significant BY component, and also promptly at substorm onset. Our findings suggest that magnetotail twisting and/or BY penetration into the magnetotail, due to subsolar reconnection with east-west orientated IMF, are the main cause of these nightside FAC asymmetries and that asymmetries also arise due to magnetotail reconnection of these twisted field lines.

AB - Principal component analysis is performed on Birkeland or field-aligned current (FAC) measurements from the Active Magnetosphere and Planetary Electrodynamics Response Experiment, to determine the response of dayside and nightside FACs to reversals in the orientation of the interplanetary magnetic field (IMF) and the occurrence of substorms. Dayside FACs respond promptly to changes in IMF BY, but the nightside response is delayed by up to an hour and can take up to 4 hr to develop fully, especially during northward IMF. Nightside FAC asymmetries grow during substorm growth phase when the IMF has a significant BY component, and also promptly at substorm onset. Our findings suggest that magnetotail twisting and/or BY penetration into the magnetotail, due to subsolar reconnection with east-west orientated IMF, are the main cause of these nightside FAC asymmetries and that asymmetries also arise due to magnetotail reconnection of these twisted field lines.

KW - currents

KW - ionosphere

KW - magnetosphere

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DO - 10.1029/2018JA025645

M3 - Article

AN - SCOPUS:85052931498

SN - 2169-9380

VL - 123

SP - 7307

EP - 7319

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

IS - 9

ER -

Timescales of Dayside and Nightside Field-Aligned Current Response to Changes in Solar Wind-Magnetosphere Coupling

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