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Abstract We investigate the response of outer radiation belt electron fluxes to different solar wind and geomagnetic indices using an interpretable machine learning method. We reconstruct the electron flux variation during 19 enhancement and 7 depletion events and demonstrate the feature attribution analysis called SHAP (SHapley Additive exPlanations) on the superposed epoch results for the first time. We find that the intensity and duration of the substorm sequence following an initial dropout determine the overall enhancement or depletion of electron fluxes, while the solar wind pressure drives the initial dropout in both types of events. Further statistical results from a data set with 71 events confirm this and show a significant correlation between the resulting flux levels and the average AL index, indicating that the observed “depletion” event can be more accurately described as a “non‐enhancement” event. Our novel SHAP‐Enhanced Superposed Epoch Analysis (SHESEA) method can offer insight in various physical systems.
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Attenuation of plasmaspheric hiss associated with the enhanced magnetospheric electric field
Abstract. We report an attenuation of hiss wave intensity in theduskside of the outer plasmasphere in response to enhanced convection anda substorm based on Van Allen Probe observations. Using test particle codes,we simulate the dynamics of energetic electron fluxes based on a realisticmagnetospheric electric field model driven by solar wind and subauroralpolarization stream. We suggest that the enhanced magnetospheric electricfield causes the outward and sunward motion of energetic electrons,corresponding to the decrease of energetic electron fluxes on the duskside,leading to the subsequent attenuation of hiss wave intensity. The resultsindicate that the enhanced electric field can significantly change theenergetic electron distributions, which provide free energy for hiss waveamplification. This new finding is critical for understanding the generationof plasmaspheric hiss and its response to solar wind and substorm activity.
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- Award ID(s):
- 1847818
- PAR ID:
- 10317664
- Date Published:
- Journal Name:
- Annales Geophysicae
- Volume:
- 39
- Issue:
- 3
- ISSN:
- 1432-0576
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5194/angeo-39-461-2021
