Meso-Scale Electrodynamic Coupling of the Earth Magnetosphere-Ionosphere System

Abstract

Within the fully integrated magnetosphere-ionosphere system, many electrodynamic processes interact with each other. We review recent advances in understanding three major meso-scale coupling processes within the system: the transient field-aligned currents (FACs), mid-latitude plasma convection, and auroral particle precipitation. (1) Transient FACs arise due to disturbances from either dayside or nightside magnetosphere. As the interplanetary shocks suddenly compress the dayside magnetosphere, short-lived FACs are induced at high latitudes with their polarity successively changing. Magnetotail dynamics, such as substorm injections, can also disturb the current structures, leading to the formation of substorm current wedges and ring current disruption. (2) The mid-latitude plasma convection is closely associated with electric fields in the system. Recent studies have unraveled some important features and mechanisms of subauroral fast flows. (3) Charged particles, while drifting around the Earth, often experience precipitating loss down to the upper atmosphere, enhancing the auroral conductivity. Recent studies have been devoted to developing more self-consistent geospace circulation models by including a better representation of the auroral conductance. It is expected that including these new advances in geospace circulation models could promisingly strengthen their forecasting capability in space weather applications. The remaining challenges especially in the global modeling of the circulation system are also discussed.

Energetic Particle Precipitation in Sub‐Auroral Polarization Streams

“…Precipitating relativistic electrons deposit most of their energy in the lower (below 80 km) ionosphere (in the D‐region and below, see, e.g., Pettit et al., 2023; Xu et al., 2020). Thus, they cannot directly affect the F/E‐regions where SAPS are formed (e.g., Mishin & Streltsov, 2021; Yu et al., 2022, and references therein). On the other hand, energetic ions, with energy fluxes higher than electron fluxes during this event, will deposit their energy above 100 km, well within the E‐region (Fang et al., 2013; Tian et al., 2023).…”

“…Sub‐auroral polarization streams (SAPS), and their more intense counterpart, sub‐auroral ion drifts (SAID), are often associated with the earthward transport (e.g., substorm injections or enhanced convection) of hot ions, their decoupling from electron motion due to diamagnetic drifts, and the formation of strong polarization electric fields and ionospheric flows (see the review by Mishin & Streltsov, 2021; Yu et al., 2022, and references therein). SAPS/SAID are formed between the inner edge of electron and ion plasma sheet (Anderson et al., 1993; Brandt et al., 2008), close to the plasmapause (see low‐altitude and equatorial statistical observations of SAPS/SAID, in He et al., 2014; Nishimura et al., 2022).…”

What Drove the GICs >10 A During the 17 March 2013 Event at Mäntsälä? A Novel Framework for Distinguishing the Magnetospheric Sources

“…We suggest storm-time RC dynamics and the mesoscale flows the impinge poleward of the duskside RC play a crucial role in creating sub-auroral GICs. Furthermore, Yu et al (2022) identified a modeling gap for integrating different spatial and temporal scales to achieve a comprehensive understanding of the entire system. Our approach can provide observational support to such modeling efforts.…”

Conjugate Observations of Magnetospheric and Ionospheric Phenomena During a Substorm Event

“…Recent studies highlight some progress in studies of magnetosphere‐ionosphere coupling. Examples include the investigation of ionospheric outflow and its consequential impact on the magnetosphere, as well as the complex interaction between various electrodynamic processes, such as transient field‐aligned currents, mid‐latitude plasma convection, and auroral particle precipitation (Glocer et al., 2009; Yu et al., 2022). Mid‐latitude regions are of particular interest because they are susceptible to space weather disturbances, resulting from magnetospheric dynamics.…”