Transport and Loss of Ring Current Electrons Inside Geosynchronous Orbit During the 17 March 2013 Storm

• Published in: Journal of geophysical research. Space physics 2019-02, Vol.124 (2), p.915-933
• Main Authors: Aseev, N. A., Shprits, Y. Y., Wang, D., Wygant, J., Drozdov, A. Y., Kellerman, A. C., Reeves, G. D.
• Format: Article
• Language: English
• Subjects: ASTRONOMY AND ASTROPHYSICS; Atmospheric models; Boundary conditions; Chorus waves; Computer simulation; Convection; Diffusion; Diffusion coefficient; Diffusion rate; Dynamics; Earth; Earth atmosphere; Earth magnetosphere; Electric fields; Electron radiation; electron transport; ensemble modeling; Geomagnetic storms; Geomagnetism; Geosynchronous orbits; heliospheric and magnetospheric physics; inner magnetosphere; Ionosphere; Magnetic fields; Magnetic Storms; Magnetic Storms and Substorms; Magnetosphere; Magnetosphere: Inner; magnetospheric convection; Magnetospheric Physics; Mathematical models; Natural Hazards; Numerical Modeling; Orbital mechanics; Parameter uncertainty; Particle physics; Plasma Convection; Plasma waves; Polarization; Radiation; Ring Current; ring current electrons; Ring currents; Satellite data; Satellite observation; Space density; Space Weather; Storms; Streams; Transport processes; Wave models; wave-particle interactions
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2018JA026031

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 Alle