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Empirical selection of Auroral Kilometric Radiation during a multipoint remote observation with Wind and Cassini
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  • James E Waters,
  • Caitriona M Jackman,
  • Laurent Lamy,
  • Baptiste Cecconi,
  • Xavier Bonnin,
  • Daniel Whiter,
  • Karine Issautier
James E 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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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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Daniel Whiter
University of Southampton
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Karine Issautier
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Auroral Kilometric Radiation (AKR) is radio emission that originates in particle acceleration regions along magnetic field lines, coinciding with discrete auroral arcs. Found in both hemispheres, an increase in the amplitude of a particular AKR source denotes the strengthening of parallel electric fields in the auroral zone, while the emission frequency gives insight into source region morphology. AKR viewing geometry is complex due to the confinement of the source regions to nightside local times and the anisotropy of the beaming pattern, so observations are highly dependent on spacecraft viewing position. We present a novel, empirical technique that selects AKR emission from remote radio observations made with the spin-axis aligned antenna of the Wind/WAVES instrument, based on the rapidly varying amplitude of AKR across spacecraft spin timescales. This selection is applied to 30 days of data in 1999, during which the Cassini spacecraft flew close to Earth and recorded AKR for the majority of the period, while the Wind spacecraft completed close to two, precessing petal orbits. We examine the flux density and integrated power, which gives an occurrence distribution with spacecraft local time that is typical of AKR, with an increase in power of around $10^{3}$ Wsr$^{-1}$ between dayside and nightside observations. We also find a statistically significant ($p < 10^{-5}$), previously observed diurnal modulation of the AKR integrated power for the period, further verifying the empirical selection of AKR and showing the promise of its application to larger subsets of Wind/WAVES observations.
Oct 2021Published in Journal of Geophysical Research: Space Physics volume 126 issue 10. 10.1029/2021JA029425