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Differentiating Between Simultaneous Loss Drivers in Earth’s Outer Radiation Belt: Multi Dimensional Phase Space Density Analysis
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  • Frances A Staples,
  • Qianli Ma,
  • Adam C Kellerman,
  • I. Jonathan Rae,
  • Colin Forsyth,
  • Jasmine Kaur Sandhu,
  • Jacob Bortnik
Frances A Staples
University of California Los Angeles

Corresponding Author:[email protected]

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Qianli Ma
University of California Los Angeles
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Adam C Kellerman
University of California Los Angeles
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I. Jonathan Rae
Northumbria University
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Colin Forsyth
Mullard Space Science Laboratory, University College London
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Jasmine Kaur Sandhu
Northumbria University
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Jacob Bortnik
University of California Los Angeles
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Abstract

We analyzed the contribution of electromagnetic ion cyclotron (EMIC) wave driven electron loss to a flux dropout event in September 2017. The evolution of electron phase space density (PSD) through the dropout showed the formation of a radially peaked PSD profile as electrons were lost at high L*, resembling distributions created by magnetopause shadowing. By comparing 2D Fokker Planck simulations of pitch angle diffusion to the observed change in PSD, we found that the μ and K of electron loss aligned with maximum scattering rates at dropout onset. We conclude that, during this dropout event, EMIC waves produced substantial electron loss. Because pitch angle diffusion occurred on closed drift paths near the last closed drift shell, no radial PSD minimum was observed. Therefore, the radial PSD gradients resembled solely magnetopause shadowing loss, even though the local pitch angle scattering produced electron losses of several orders of magnitude of the PSD.
06 Sep 2023Submitted to ESS Open Archive
11 Sep 2023Published in ESS Open Archive