Statistical azimuthal structuring of the substorm onset arc: Implications for the onset mechanism

Kalmoni, N. M. E., Rae, Jonathan, Murphy, K. R., Forsyth, C., Watt, Clare and Owen, C. J. (2017) Statistical azimuthal structuring of the substorm onset arc: Implications for the onset mechanism. Geophysical Research Letters, 44 (5). pp. 2078-2087. ISSN 0094-8276

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The onset of an auroral substorm is generally thought to occur on a quiet, homogeneous auroral arc. We present a statistical study of independently selected substorm onset arcs and find that over 90% of the arcs studied have resolvable characteristic spatial scales in the form of auroral beads. We find that the vast majority (~88%) of auroral beads have small amplitudes relative to the background, making them invisible without quantitative analysis. This confirms that auroral beads are highly likely to be ubiquitous to all onset arcs, rather than a special case phenomena as previously thought. Moreover, as these auroral beads grow exponentially through onset, we conclude that a magnetospheric plasma instability is fundamental to substorm onset itself.

Item Type: Article
Uncontrolled Keywords: N.M.E.K. is supported by a Science and Technology Facilities Council (STFC) PhD studentship grant ST/K50239X/1. C.E.J.W. is supported by STFC grant ST/M000885/1. C.F. is supported by NERC IRF NE/N014480/1. K.R.M. is partially supported by an NSERC Postdoctoral Fellowship. I.J.R. and C.J.O. are supported by STFC consolidated grant to MSSL, ST/N0007722/1. I.J.R. is also supported by National Environment Research Council (NERC) NE/L007495/1.
Subjects: F300 Physics
F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Elena Carlaw
Date Deposited: 15 Feb 2021 13:06
Last Modified: 31 Jul 2021 15:00

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