Nonlinear Wave‐Particle Interaction Effects on Radiation Belt Electron Dynamics in 9 October 2012 Storm.

Autor: Kondrashov, D.1 (AUTHOR) dkondras@atmos.ucla.edu, Drozdov, A. Y.2 (AUTHOR), Shprits, Y.2,3 (AUTHOR)
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Zdroj: Journal of Geophysical Research. Space Physics. Sep2024, Vol. 129 Issue 9, p1-8. 8p.
Abstrakt: We study the geomagnetic storm of 9 October 2012, where it had been generally accepted that the resulting prominent outer radiation belt electron acceleration throughout the storm is due to whistler‐mode chorus waves. This storm has been studied previously by two‐dimensional Fokker–Planck numerical simulations with data‐driven quasi‐linear (QL) diffusion rates. However, possible nonlinear (NL) resonant interaction effects on electron flux dynamics haven't been looked at yet. This study aims to fill this gap by demonstrating that theory‐informed rescaling of QL diffusion rates accounting for contributions of NL resonant interactions helps to reproduce better observed increase of electron fluxes by diffusion simulations. We use machine learning, uncertainty quantification (UQ), physics‐perturbed ensemble of VERB simulations and Van Allen Probes observations to identify optimal rescaling of quasi‐linear diffusion rates. Plain Language Summary: Characterizing and understanding the rapid enhancements of relativistic electrons, which can damage Earth‐orbiting satellites, is critical for predicting the near‐Earth radiation environment and is an integral part of space weather. Electromagnetic wave‐particle interactions provide the dominant mechanism for changes in the outer radiation belt structure. For small wave amplitudes and a broad wave spectrum, such interactions can be described by the quasi‐linear theory, leading to the Fokker‐Planck diffusion equation for the phase space density of electrons. However, for high amplitude waves, non‐linear interaction effects can also change the distributions of energetic electrons in the heart of the outer radiation belt and must be accounted for. In this study, a nonlinear description of electron dynamics is enabled by theory‐informed rescaling of quasi‐linear diffusion coefficients in the Fokker‐Planck diffusion equation to accurately capture the rapid acceleration of electrons during the geomagnetic storm of 9 October 2012. Key Points: Evidence of nonlinear wave‐particle resonant interaction effects for electron flux dynamics in the geomagnetic storm of 9 October 2012Theory‐informed rescaling of quasi‐linear diffusion rates in VERB simulations helps to reproduce better observed increase of electron fluxesUncertainty quantification, machine learning and physics‐perturbed ensemble of VERB simulations enables to identify optimal rescaling factor [ABSTRACT FROM AUTHOR]
Databáze: GreenFILE
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