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Substorm onset latitude and the steadiness of magnetospheric convection

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Substorm onset latitude and the steadiness of magnetospheric convection. / Milan, S.; Walach, Maria-Theresia; Carter, J. A. ; Sangha, H.; Anderson, B. J.

In: Journal of Geophysical Research: Space Physics, Vol. 124, No. 3, 31.03.2019, p. 1738-1752.

Research output: Contribution to journalJournal article

Harvard

Milan, S, Walach, M-T, Carter, JA, Sangha, H & Anderson, BJ 2019, 'Substorm onset latitude and the steadiness of magnetospheric convection', Journal of Geophysical Research: Space Physics, vol. 124, no. 3, pp. 1738-1752. https://doi.org/10.1029/2018JA025969

APA

Milan, S., Walach, M-T., Carter, J. A., Sangha, H., & Anderson, B. J. (2019). Substorm onset latitude and the steadiness of magnetospheric convection. Journal of Geophysical Research: Space Physics, 124(3), 1738-1752. https://doi.org/10.1029/2018JA025969

Vancouver

Milan S, Walach M-T, Carter JA, Sangha H, Anderson BJ. Substorm onset latitude and the steadiness of magnetospheric convection. Journal of Geophysical Research: Space Physics. 2019 Mar 31;124(3):1738-1752. https://doi.org/10.1029/2018JA025969

Author

Milan, S. ; Walach, Maria-Theresia ; Carter, J. A. ; Sangha, H. ; Anderson, B. J. / Substorm onset latitude and the steadiness of magnetospheric convection. In: Journal of Geophysical Research: Space Physics. 2019 ; Vol. 124, No. 3. pp. 1738-1752.

Bibtex

@article{f0bcb801f27340bf9603d6487b20af09,
title = "Substorm onset latitude and the steadiness of magnetospheric convection",
abstract = "We study the role of substorms and steady magnetospheric convection (SMC) in magnetic flux transport in the magnetosphere, using observations of field-aligned currents by the Active Magnetosphere and Planetary Electrodynamics Response Experiment. We identify two classes of substorm, with onsets above and below 65° magnetic latitude, which display different nightside field-aligned current morphologies. We show that the low-latitude onsets develop a poleward-expanding auroral bulge, and identify these as substorms that manifest ionospheric convection-braking in the auroral bulge region as suggested by Grocott et al. (2009, https://doi.org/10.5194/angeo-27-591-2009). We show that the high-latitude substorms, which do not experience braking, can evolve into SMC events if the interplanetary magnetic field remains southward for a prolonged period following onset. We conclude that during periods of ongoing driving, the magnetosphere displays repeated substorm activity or SMC depending on the rate of driving and the open magnetic flux content of the magnetosphere prior to onset. We speculate that sawtooth events are an extreme case of repeated onsets and that substorms triggered by northward-turnings of the interplanetary magnetic field mark the cessation of periods of SMC. Our results provide a new explanation for the differing modes of response of the terrestrial system to solar wind-magnetosphere-ionosphere coupling by invoking friction between the ionosphere and atmosphere.",
keywords = "substorms, convection, field-aligned currents",
author = "S. Milan and Maria-Theresia Walach and Carter, {J. A.} and H. Sangha and Anderson, {B. J.}",
year = "2019",
month = "3",
day = "31",
doi = "10.1029/2018JA025969",
language = "English",
volume = "124",
pages = "1738--1752",
journal = "Journal of Geophysical Research: Space Physics",
issn = "2169-9402",
publisher = "Blackwell Publishing Ltd",
number = "3",

}

RIS

TY - JOUR

T1 - Substorm onset latitude and the steadiness of magnetospheric convection

AU - Milan, S.

AU - Walach, Maria-Theresia

AU - Carter, J. A.

AU - Sangha, H.

AU - Anderson, B. J.

PY - 2019/3/31

Y1 - 2019/3/31

N2 - We study the role of substorms and steady magnetospheric convection (SMC) in magnetic flux transport in the magnetosphere, using observations of field-aligned currents by the Active Magnetosphere and Planetary Electrodynamics Response Experiment. We identify two classes of substorm, with onsets above and below 65° magnetic latitude, which display different nightside field-aligned current morphologies. We show that the low-latitude onsets develop a poleward-expanding auroral bulge, and identify these as substorms that manifest ionospheric convection-braking in the auroral bulge region as suggested by Grocott et al. (2009, https://doi.org/10.5194/angeo-27-591-2009). We show that the high-latitude substorms, which do not experience braking, can evolve into SMC events if the interplanetary magnetic field remains southward for a prolonged period following onset. We conclude that during periods of ongoing driving, the magnetosphere displays repeated substorm activity or SMC depending on the rate of driving and the open magnetic flux content of the magnetosphere prior to onset. We speculate that sawtooth events are an extreme case of repeated onsets and that substorms triggered by northward-turnings of the interplanetary magnetic field mark the cessation of periods of SMC. Our results provide a new explanation for the differing modes of response of the terrestrial system to solar wind-magnetosphere-ionosphere coupling by invoking friction between the ionosphere and atmosphere.

AB - We study the role of substorms and steady magnetospheric convection (SMC) in magnetic flux transport in the magnetosphere, using observations of field-aligned currents by the Active Magnetosphere and Planetary Electrodynamics Response Experiment. We identify two classes of substorm, with onsets above and below 65° magnetic latitude, which display different nightside field-aligned current morphologies. We show that the low-latitude onsets develop a poleward-expanding auroral bulge, and identify these as substorms that manifest ionospheric convection-braking in the auroral bulge region as suggested by Grocott et al. (2009, https://doi.org/10.5194/angeo-27-591-2009). We show that the high-latitude substorms, which do not experience braking, can evolve into SMC events if the interplanetary magnetic field remains southward for a prolonged period following onset. We conclude that during periods of ongoing driving, the magnetosphere displays repeated substorm activity or SMC depending on the rate of driving and the open magnetic flux content of the magnetosphere prior to onset. We speculate that sawtooth events are an extreme case of repeated onsets and that substorms triggered by northward-turnings of the interplanetary magnetic field mark the cessation of periods of SMC. Our results provide a new explanation for the differing modes of response of the terrestrial system to solar wind-magnetosphere-ionosphere coupling by invoking friction between the ionosphere and atmosphere.

KW - substorms

KW - convection

KW - field-aligned currents

U2 - 10.1029/2018JA025969

DO - 10.1029/2018JA025969

M3 - Journal article

VL - 124

SP - 1738

EP - 1752

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

SN - 2169-9402

IS - 3

ER -