| Autor: |
Aseev, N. A., Shprits, Y. Y., Wang, D., Wygant, J., Drozdov, A. Y., Kellerman, A. C., Reeves, G. D. |
| Předmět: |
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| Zdroj: |
Journal of Geophysical Research. Space Physics; Feb2019, Vol. 124 Issue 2, p915-933, 19p |
| Abstrakt: |
Ring current electrons (1–100 keV) have received significant attention in recent decades, but many questions regarding their major transport and loss mechanisms remain open. In this study, we use the four‐dimensional Versatile Electron Radiation Belt code to model the enhancement of phase space density that occurred during the 17 March 2013 storm. Our model includes global convection, radial diffusion, and scattering into the Earth's atmosphere driven by whistler‐mode hiss and chorus waves. We study the sensitivity of the model to the boundary conditions, global electric field, the electric field associated with subauroral polarization streams, electron loss rates, and radial diffusion coefficients. The results of the code are almost insensitive to the model parameters above 4.5 RERE, which indicates that the general dynamics of the electrons between 4.5 RE and the geostationary orbit can be explained by global convection. We found that the major discrepancies between the model and data can stem from the inaccurate electric field model and uncertainties in lifetimes. We show that additional mechanisms that are responsible for radial transport are required to explain the dynamics of ≥40‐keV electrons, and the inclusion of the radial diffusion rates that are typically assumed in radiation belt studies leads to a better agreement with the data. The overall effect of subauroral polarization streams on the electron phase space density profiles seems to be smaller than the uncertainties in other input parameters. This study is an initial step toward understanding the dynamics of these particles inside the geostationary orbit. Plain Language Summary: The dynamics of the ring current electrons is a competition between loss and transport processes in the Earth's inner magnetosphere. These processes remain poorly understood due to difficulties of in situ particle measurements. Given the scarcity of satellite data, numerical modeling is a powerful approach that allows us to gain a deeper insight into the behavior of the ring current electrons. In this work, we investigate which processes dominate the dynamics of these particles within the geostationary orbit. We use the four‐dimensional Versatile Electron Radiation Belt code to model electron loss and transport processes during 17 March 2013 geomagnetic storm. To understand the significance of the model uncertainty, we run an ensemble of simulations with different model parameters and compare results with the Van Allen Probe satellite observations. We show that the global convective electric and magnetic fields control the transport of the ring current electrons inside the geostationary orbit. This work is a basis for future studies, which will be extended further away from the Earth and include more comprehensive plasma wave models. Key Points: Ring current electron dynamics within geostationary orbit is modeled and the sensitivity of the model to the input parameters is exploredGlobal convective electron transport from geostationary orbit to 4.5 RE can explain Van Allen Probe observationsModel results below 4.5 RE are most sensitive to the electric field and electron lifetimes [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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