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Identifying Typical Relativistic Electron Pitch Angle Distributions: Evolution During Geomagnetic Storms
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  • Shannon Killey,
  • I. Jonathan Rae,
  • Andrew W Smith,
  • Sarah N Bentley,
  • Clare E. J. Watt,
  • Suman Chakraborty,
  • Louis Godwin Ozeke,
  • Maria-Theresia Walach,
  • Jasmine Kaur Sandhu,
  • Dovile Rasinskaite
Shannon Killey
Northumbria University

Corresponding Author:[email protected]

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I. Jonathan Rae
Northumbria University
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Andrew W Smith
Northumbria University
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Sarah N Bentley
Northumbria University
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Clare E. J. Watt
Northumbria University
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Suman Chakraborty
Northumbria University
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Louis Godwin Ozeke
University of Alberta
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Maria-Theresia Walach
Lancaster University
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Jasmine Kaur Sandhu
University of Leicester
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Dovile Rasinskaite
Northumbria University
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Abstract

Van Allen radiation belt electron dynamics are governed by a wide range of physical processes that can simultaneously drive acceleration, transport and loss. However, each individual process can be linked to a specific energy-dependent pitch angle distribution (PAD). We employ a new, unsupervised machine learning technique on 7-years of Van Allen Probe Relativistic Electron-Proton Telescope data and discover that six PADs, two each of: pancake, butterfly, and flattop, successfully describe >70% of classified relativistic PADs. We investigate the occurrence and storm-time evolution of each PAD through 45 geomagnetic storms. We find new populations of PADs, including: “shadowing-like” and wave-particle interaction signatures at low-L, and radial diffusion and substorm injections at higher-L, as well as determining that wave-particle interaction dominated PADs are swamped by radial diffusion processes through geomagnetic storms. Our results clearly demonstrate that PAD characterisation is a key component of understanding Van Allen radiation belt electron dynamics
14 Jun 2024Submitted to ESS Open Archive
14 Jun 2024Published in ESS Open Archive