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The spatial localisation of storm-time ULF waves due to plasmaspheric plumes and implications for calculating radial diffusion
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  • Jasmine Kaur Sandhu,
  • Kyle Robert Murphy,
  • I. Jonathan Rae,
  • Alexander William Degeling,
  • Adnane Osmane,
  • David Paul Hartley,
  • Leonid Olifer
Jasmine Kaur Sandhu
University of Leicester

Corresponding Author:[email protected]

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Kyle Robert Murphy
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I. Jonathan Rae
Northumbria University
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Alexander William Degeling
Shandong University
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Adnane Osmane
University of Helsinki
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David Paul Hartley
University of Iowa
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Leonid Olifer
University of Alberta
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The generation and propagation of Ultra Low Frequency (ULF) waves are intrinsically coupled to the cold plasma population in the terrestrial magnetosphere. During geomagnetic storms, extreme reconfigurations of the cold plasma creates a complex and dynamic system that drastically modifies this coupling. The extent and manner in which this coupling is affected remains an open question. In this report, we assess the coupling between ULF waves and cold plasmaspheric plumes during geomagnetic storms, and investigate the implications for ULF wave-driven radial transport of the outer radiation belt population. We present a series of event studies of Van Allen Probes observations. For each event, we use inferred measurements of the cold plasma density during plume crossings, in combination with magnetic and electric field observations of ULF waves. The event studies show very different, and at times contrasting, wave behaviour. This includes events where ULF waves appear to be spatially confined within plume structures. Initial estimates show that the localised patches of ULF wave power have significant implications for radial diffusion processes, and highlights the need for caution in estimating radial diffusion coefficients. We suggest that the cold plasma dynamics is an important source of uncertainty in radial diffusion models, and understanding cold plasma-ULF wave coupling is a critical area of future investigations.
05 Mar 2024Submitted to ESS Open Archive
05 Mar 2024Published in ESS Open Archive