Magnetosphere‐Ionosphere Coupling of Precipitated Electrons in Diffuse Aurora Driven by Time Domain Structures

Abstract

The diffuse aurora precipitations provide more than 70% of the energy flux from the magnetosphere to the ionosphere (e.g., Newell et al., 2009). Based on the rigorous FAST spacecraft analysis provided by Dombeck et al. (2018), this percentage of the energy coming from the diffuse aurora is potentially a large overstatement. It is, nonetheless, still substantial and likely in the range of ∼30%-70%. These precipitations modify the ionosphere conductance, affecting thereby the convection electric field in the magnetosphere (e.g., Hardy et al., 1989). Therefore, the understanding of the sources and modeling of the fluxes of diffuse aurora precipitations represent the substantial interest for modeling the magnetosphere-ionosphere coupling (e.g., Yu et al., 2016).It is widely accepted that the diffuse aurora is primarily produced by magnetospheric electrons scattered into the loss cone by wave-particle resonant interaction processes, either driven by electron-cyclotron harmonic (ECH) waves at radial distances larger than ∼8 Earth radii (

Dayside Low Energy Electron Precipitation Driven by Hiss Waves in the Presence of Ionospheric Photoelectrons

“…(2021) in order to identify the role of ionospheric photo‐, secondary, and primary degraded electrons in the formation of lower energy electron spectra that is driven by hiss waves in the plasmaspheric plumes. The theoretical results presented in this manuscript are based on the gyro‐averaged kinetic STET code developed by Khazanov (2010), that was further modified to include different kind of wave‐particle interaction processes in the magnetosphere (Khazanov, Shen, et al., 2021; Khazanov, Glocer, & Chu, 2021), and the bounce‐averaged Fokker Plank code developed by Ma et al. (2012), Ma, Li, Thorne, Bortnik, et al.…”

“…Following Khazanov, Shen, et al. (2021) and Khazanov, Glocer, and Chu (2021), we fit the energy spectrum of trapped electron fluxes at 1–30 keV energies using a Maxwellian‐type distribution function (blue), with the fitting coefficients shown in Figures 1e and 1f. The fitted electron flux distribution is used in the STET code.…”

“…To simulate electron precipitation that are triggered by hiss waves, STET code will be used in the same configuration as in the previous studies with electron cyclotron harmonic (ECH) (Khazanov at al., 2015) and whistler‐mode chorus (Khazanov et al., 2017) waves, as well as modeling of electron interaction with time domain structures (TDSs) (Khazanov, Shen, et al., 2021). The summary of all these wave activities (except TDSs) is shown in the modified qualitative picture (Figure 3) that was used in our previous studies (Khazanov et al., 2020; Khazanov, Shen, et al., 2021, Khazanov, Glocer, & Chu, 2021). Interaction between electrons and all these waves starts in the vicinity of the geomagnetic equator with initiation of Precipitating Primary Flux as shown in Figure 3.…”

“…It solves gyro‐average kinetic equation for the suprathermal electrons (SE) for the energies above 1 eV and include relativistic effects (Khazanov, 2010). This kinetic equation for the SE can be presented as (Khazanov, Shen, et al., 2021, Khazanov, Glocer, & Chu, 2021) $$$\frac{1}{v}\frac{\partial {\Phi}}{\partial t}+\mu \frac{\partial {\Phi}}{\partial s}-\frac{1-{\mu }^{2}}{2}(\frac{1}{B}\frac{\partial B}{\partial s}-\frac{F}{E})\frac{\partial {\Phi}}{\partial \mu }+EF\mu \hspace*{.5em}\frac{\partial }{\partial E}(\frac{{\Phi}}{E})\hspace*{.5em}=Q+\langle S\rangle ,$$$ where $${\Phi}$$ = 2Ef/m 2 is the SE flux, v is SE velocity, t is time, s is the distance along the field line, E is the particle energy, m is the particle mass, and $$\mu $$ is the cosine of the pitch angle. F is the electric field force, Q is the SE source term, and 〈 S 〉 , which includes collision integrals, represents interactions with thermal electrons and ions, scattering with neutral particles, and wave‐particle interactions.…”

“…During these processes they lose their energy and degrade toward 100 eV energies. They also experience elastic collision with the neutral particles and backscatter toward the magnetosphere and the conjugate ionospheric region (Khazanov, Shen, et al., 2021, Khazanov, Glocer, & Chu, 2021).…”