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A perspective on substorm dynamics using 10 years of Auroral Kilometric Radiation observations from Wind
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  • James Edwin Waters,
  • Caitriona M Jackman,
  • Daniel Whiter,
  • Colin Forsyth,
  • Alexandra R Fogg,
  • Laurent Lamy,
  • Baptiste Cecconi,
  • Xavier Bonnin,
  • Karine Issautier
James Edwin Waters
University of Southampton

Corresponding Author:j.waters@soton.ac.uk

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Caitriona M Jackman
Dublin Institute for Advanced Studies
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Daniel Whiter
University of Southampton
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Colin Forsyth
University College London
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Alexandra R Fogg
School of Cosmic Physics, DIAS Dunsink Observatory, Dublin Institute For Advanced Studies
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Laurent Lamy
LESIA, Observatoire de Paris, CNRS, PSL
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Baptiste Cecconi
Observatoire de Paris
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Xavier Bonnin
Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique
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Karine Issautier
LESIA
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Abstract

We study 10 years (1995-2004 inclusive) of auroral kilometric radiation (AKR) radio emission data from the Wind spacecraft to examine the link between AKR and terrestrial substorms. We use substorm lists based on parameters including ground magnetometer signatures and geosynchronous particle injections as a basis for superposed epoch analyses of the AKR data. The results for each list show a similar, clear response of the AKR power around substorm onset. For nearly all event lists, the average response shows that the AKR power begins to increase around 20 minutes prior to expansion phase onset, as defined by the respective lists. The analysis of the spectral parameters of AKR bursts show that this increase in power is due to an extension of the source region to higher altitudes, which also precedes expansion phase onset by 20 minutes. Our observations show that the minimum frequency channel that observes AKR at this time, on average, is 60 kHz. AKR visibility is highly sensitive to observing spacecraft location, and the biggest radio response to substorm onset is seen in the 2100 - 0300 hr LT sector.