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An Enhanced "Flux‐Corrected Transport"‐Based Plasmasphere Refilling Model.

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Title: An Enhanced "Flux‐Corrected Transport"‐Based Plasmasphere Refilling Model.
Authors: Fitzpatrick, Jaden1 (AUTHOR) jaden.fitzpatrick@lasp.colorado.edu, Chatterjee, Kausik1,2,3 (AUTHOR), Maruyama, Naomi1 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. May2026, Vol. 131 Issue 5, p1-11. 11p.
Subject Terms: *Hydrodynamics, *Magnetic storms, Electron temperature, Ion flow dynamics, Ionospheric plasma
Abstract: A previously developed multi‐ion, two‐stream Flux‐Corrected Transport (FCT) hydrodynamic model for plasmasphere refilling has been extended to incorporate self‐consistent electron temperature evolution. The past assumption of a constant temperature along the modeled flux tube has been replaced by solving the electron energy equation, permitting spatially and temporally varying temperature. This improvement provides a more physically complete representation of the pressure and ambipolar electric‐field gradients that influence ion transport. The extended model allows us to investigate two‐stage refilling behavior established by prior observations and simulations. The model continues to reproduce the expected dominance of H+ ${\mathrm{H}}^{+}$, enhanced early‐time O+ ${\mathrm{O}}^{+}$ contributions, and the coupling between H+ ${\mathrm{H}}^{+}$ and He+ ${\text{He}}^{+}$ through the ambipolar electric field during the transition between stages. Sensitivity experiments with modified initial ion concentrations, including cases representing seasonal effects, highlight the distinct roles of each ion species in shaping the refilling trajectory. Comparisons across L‐shells 3 and 4 further confirm the robustness of the model framework for future extension to three‐dimensional geometries. Overall, by incorporating more realistic temperature variations, this enhanced model strengthens the physical understanding for interpreting complex multi‐ion transport processes during plasmasphere recovery following geomagnetic storms. Plain Language Summary: The plasmasphere hosts cold, dense plasma in a torus‐shape surrounding the earth. Solar storms cause most of the plasmasphere's mass to erode away. The ionosphere is the region below the plasmasphere that supplies plasma to replace what was lost from a solar storm via plasmasphere refilling. A model of plasmasphere refilling that considers two streams of multiple ions from the ionosphere now solves the electron energy equation. This allows temperature to depend on space and time instead of the previous nonphysical assumption of constant temperature. The extended model allows us to investigate two‐stage refilling behavior established by prior observations and simulations. The impact of each ion on each stage of refilling was analyzed and further isolated by simulating refilling events with modified initial ion concentrations, including those reflecting seasonal variations. Comparisons across altitude further confirm the robustness of the model framework for future extension to three‐dimensional geometries. Overall, by incorporating more realistic temperature variations, this enhanced model strengthens the physical understanding for interpreting the complex transport of ions during plasmasphere recovery following solar storms. Key Points: A multi‐ion, two‐stream, hydrodynamic flux‐corrected transport model is enhanced to solve electron temperature self‐consistentlyIncorporating temperature spatiotemporal variability in the model improves the characterization of two‐stage plasmasphere refillingEach ion species contributes to the two‐stage process in a unique manner [ABSTRACT FROM AUTHOR]
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Abstract:A previously developed multi‐ion, two‐stream Flux‐Corrected Transport (FCT) hydrodynamic model for plasmasphere refilling has been extended to incorporate self‐consistent electron temperature evolution. The past assumption of a constant temperature along the modeled flux tube has been replaced by solving the electron energy equation, permitting spatially and temporally varying temperature. This improvement provides a more physically complete representation of the pressure and ambipolar electric‐field gradients that influence ion transport. The extended model allows us to investigate two‐stage refilling behavior established by prior observations and simulations. The model continues to reproduce the expected dominance of H+ ${\mathrm{H}}^{+}$, enhanced early‐time O+ ${\mathrm{O}}^{+}$ contributions, and the coupling between H+ ${\mathrm{H}}^{+}$ and He+ ${\text{He}}^{+}$ through the ambipolar electric field during the transition between stages. Sensitivity experiments with modified initial ion concentrations, including cases representing seasonal effects, highlight the distinct roles of each ion species in shaping the refilling trajectory. Comparisons across L‐shells 3 and 4 further confirm the robustness of the model framework for future extension to three‐dimensional geometries. Overall, by incorporating more realistic temperature variations, this enhanced model strengthens the physical understanding for interpreting complex multi‐ion transport processes during plasmasphere recovery following geomagnetic storms. Plain Language Summary: The plasmasphere hosts cold, dense plasma in a torus‐shape surrounding the earth. Solar storms cause most of the plasmasphere's mass to erode away. The ionosphere is the region below the plasmasphere that supplies plasma to replace what was lost from a solar storm via plasmasphere refilling. A model of plasmasphere refilling that considers two streams of multiple ions from the ionosphere now solves the electron energy equation. This allows temperature to depend on space and time instead of the previous nonphysical assumption of constant temperature. The extended model allows us to investigate two‐stage refilling behavior established by prior observations and simulations. The impact of each ion on each stage of refilling was analyzed and further isolated by simulating refilling events with modified initial ion concentrations, including those reflecting seasonal variations. Comparisons across altitude further confirm the robustness of the model framework for future extension to three‐dimensional geometries. Overall, by incorporating more realistic temperature variations, this enhanced model strengthens the physical understanding for interpreting the complex transport of ions during plasmasphere recovery following solar storms. Key Points: A multi‐ion, two‐stream, hydrodynamic flux‐corrected transport model is enhanced to solve electron temperature self‐consistentlyIncorporating temperature spatiotemporal variability in the model improves the characterization of two‐stage plasmasphere refillingEach ion species contributes to the two‐stage process in a unique manner [ABSTRACT FROM AUTHOR]
ISSN:21699380
DOI:10.1029/2025JA034915