Radial diffusion driven by spatially localized ULF waves in the Earth's magnetosphere

Adnane Osmane; Jasmine K. Sandhu; Tom Elsden; Oliver Allanson; Lucile Turc

doi:10.1029/2024JA033393

Radial diffusion driven by spatially localized ULF waves in the Earth's magnetosphere

Adnane Osmane^*
, Jasmine K. Sandhu
, Tom Elsden
, Oliver Allanson
, Lucile Turc

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

Ultra-Low Frequency (ULF) waves are critical drivers of particle acceleration and loss in the Earth's magnetosphere. While statistical models of ULF-induced radial transport have traditionally assumed that the waves are uniformly distributed across magnetic local time (MLT), decades of observational evidence show significant MLT localization of ULF waves in the Earth's magnetosphere. This study presents, for the first time, a quasi-linear radial diffusion coefficient accounting for localized ULF waves. Our results reveal that when ULF waves cover more than 30% of the MLT, the radial diffusion efficiency is comparable to that of uniform wave distributions. However, when ULF waves are confined within 10% of the drift orbit, the transport coefficient is enhanced by 10%–25%, indicating that narrowly localized ULF waves are efficient drivers of radial diffusion.

Original language	English
Article number	e2024JA033393
Number of pages	14
Journal	Journal of Geophysical Research: Space Physics
Volume	130
Issue number	3
DOIs	https://doi.org/10.1029/2024JA033393
Publication status	Published - 12 Mar 2025

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10.1029/2024JA033393Licence: CC BY-NC-ND

Osmane_2025_JGRSP_Radial-diffusion-ULF-waves-magnetosphere_CC
© 2025. The Author(s). This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License (https://creativecommons.org/licenses/by-nc-nd/4.0/), which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
Final published version, 631 KBLicence: CC BY-NC-ND

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@article{3df38e96299f41648cfc692645c8226c,

title = "Radial diffusion driven by spatially localized ULF waves in the Earth's magnetosphere",

abstract = "Ultra-Low Frequency (ULF) waves are critical drivers of particle acceleration and loss in the Earth's magnetosphere. While statistical models of ULF-induced radial transport have traditionally assumed that the waves are uniformly distributed across magnetic local time (MLT), decades of observational evidence show significant MLT localization of ULF waves in the Earth's magnetosphere. This study presents, for the first time, a quasi-linear radial diffusion coefficient accounting for localized ULF waves. Our results reveal that when ULF waves cover more than 30\% of the MLT, the radial diffusion efficiency is comparable to that of uniform wave distributions. However, when ULF waves are confined within 10\% of the drift orbit, the transport coefficient is enhanced by 10\%–25\%, indicating that narrowly localized ULF waves are efficient drivers of radial diffusion.",

author = "Adnane Osmane and Sandhu, \{Jasmine K.\} and Tom Elsden and Oliver Allanson and Lucile Turc",

note = "Funding: Support for AO was provided by the University of Helsinki and the Research Council of Finland profiling action Matter and Materials (Grant 318913). OA would like to acknowledge financial support from the University of Birmingham, the University of Exeter, and also from the United Kingdom Research and Innovation (UKRI) Natural Environment Research Council (NERC) Independent Research Fellowship NE/V013963/1 and NE/V013963/2. The work of LT is funded by the European Union (ERC grant WAVESTORMS - 101124500). LT also acknowledges support from the Research Council of Finland (Grant 322544).",

year = "2025",

month = mar,

day = "12",

doi = "10.1029/2024JA033393",

language = "English",

volume = "130",

journal = "Journal of Geophysical Research: Space Physics",

issn = "2169-9402",

publisher = "John Wiley \& Sons, Ltd",

number = "3",

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TY - JOUR

T1 - Radial diffusion driven by spatially localized ULF waves in the Earth's magnetosphere

AU - Osmane, Adnane

AU - Sandhu, Jasmine K.

AU - Elsden, Tom

AU - Allanson, Oliver

AU - Turc, Lucile

N1 - Funding: Support for AO was provided by the University of Helsinki and the Research Council of Finland profiling action Matter and Materials (Grant 318913). OA would like to acknowledge financial support from the University of Birmingham, the University of Exeter, and also from the United Kingdom Research and Innovation (UKRI) Natural Environment Research Council (NERC) Independent Research Fellowship NE/V013963/1 and NE/V013963/2. The work of LT is funded by the European Union (ERC grant WAVESTORMS - 101124500). LT also acknowledges support from the Research Council of Finland (Grant 322544).

PY - 2025/3/12

Y1 - 2025/3/12

N2 - Ultra-Low Frequency (ULF) waves are critical drivers of particle acceleration and loss in the Earth's magnetosphere. While statistical models of ULF-induced radial transport have traditionally assumed that the waves are uniformly distributed across magnetic local time (MLT), decades of observational evidence show significant MLT localization of ULF waves in the Earth's magnetosphere. This study presents, for the first time, a quasi-linear radial diffusion coefficient accounting for localized ULF waves. Our results reveal that when ULF waves cover more than 30% of the MLT, the radial diffusion efficiency is comparable to that of uniform wave distributions. However, when ULF waves are confined within 10% of the drift orbit, the transport coefficient is enhanced by 10%–25%, indicating that narrowly localized ULF waves are efficient drivers of radial diffusion.

AB - Ultra-Low Frequency (ULF) waves are critical drivers of particle acceleration and loss in the Earth's magnetosphere. While statistical models of ULF-induced radial transport have traditionally assumed that the waves are uniformly distributed across magnetic local time (MLT), decades of observational evidence show significant MLT localization of ULF waves in the Earth's magnetosphere. This study presents, for the first time, a quasi-linear radial diffusion coefficient accounting for localized ULF waves. Our results reveal that when ULF waves cover more than 30% of the MLT, the radial diffusion efficiency is comparable to that of uniform wave distributions. However, when ULF waves are confined within 10% of the drift orbit, the transport coefficient is enhanced by 10%–25%, indicating that narrowly localized ULF waves are efficient drivers of radial diffusion.

U2 - 10.1029/2024JA033393

DO - 10.1029/2024JA033393

M3 - Article

SN - 2169-9402

VL - 130

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

IS - 3

M1 - e2024JA033393

ER -

Radial diffusion driven by spatially localized ULF waves in the Earth's magnetosphere

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