Global Driving of Auroral Precipitation: 1. Balance of Sources

Abstract

High-latitude precipitation of charged particles is a crucial driver of ionospheric electrodynamics (e.g., Kivelson & Russell, 1995). These particles precipitate from the near-Earth plasma environment to form the aurora, and enhance the electrical conductance in the polar regions (e.g., Schunk & Nagy, 2009). Auroral precipitation is broadly defined into two types: diffuse and discrete aurora. Particles scattered into the loss cone by plasma waves create the diffuse aurora (Nishimura et al., 2020a and references therein). Diffuse particles precipitate into the upper atmosphere without the need of acceleration, and can consist of both electrons (e.g., Evans & Moore, 1979) and ions (e.g., Sergeev et al., 1983). Conversely, the discrete aurora is generated by particles that are accelerated into the ionosphere (e.g., Korth et al., 2014). These particles can be accelerated by geomagnetic field-aligned electric fields (monoenergetic; e.g., Evans, 1974;Knight, 1973) or by dispersive Alfvén waves (broadband; e.g., Chaston et al., 2003;Ergun et al., 1998). The conductance enhancements caused by auroral precipitation are important to investigative studies of magnetosphere-ionosphere coupling (e.g., Öztürk et al., 2020), since it regulates the closure of field-aligned currents (FACs;Iijima & Potemra, 1976) and maintain the nonlinear feedback

Statistics of geomagnetic storms: Global simulations perspective

“…The CMEE model for auroral conductances allows for a larger range of values, which lead to lower cross-polar potential values (as a result of currents closing between R1 and R2 currents), and larger ground magnetic perturbation values (Mukhopadhyay et al, 2020). However, accurate modeling of both the diffuse and discrete sources and inclusion of their ionospheric impacts into the global simulations is still work in progress (Mukhopadhyay et al, 2022).…”

Unified Theory of the Arc Auroras: Formation Mechanism of the Arc Auroras Conforming General Principles of Convection and FAC Generation

“…The difficult point is to get higher resolution in the M‐I coupling process. The Lyon‐Fedder‐Mobarry (LFM) model (Ohma et al., 2021; Pham et al., 2016; Sorathia et al., 2020) has a considerable ability for the calculation of the ionospheric FAC, while others such as the Grand Unified Magnetosphere‐Ionosphere Coupling Simulation (GUMICS) (Lakka et al., 2018), Block Adaptive Tree Solar‐wind Roe‐type Upwind Scheme (BATSRUS) (Mukhopadhyay et al., 2022; Ozturk et al., 2017; Toth et al., 2011), and Open Geospace General Circulation Model (Cramer et al., 2017; Ferdousi et al., 2021; Kavosi et al., 2018; Li et al., 2017) provide minimum required reproduction of the ionospheric FAC to study auroral problems from comparison with observations. The REPPU code has pretty better performance in the M‐I coupling calculation than above models.…”

Ionospheric Conductances Due To Electron and Ion Precipitations: A Comparison Between EISCAT and DMSP Estimates

“…In addition to electron precipitation, ion precipitation also enhances ionospheric electron density and conductances (Coumans et al, 2004;Mukhopadhyay et al, 2022;Robinson et al, 2020;Yu et al, 2015). Galand and Richmond (2001) have developed empirical formulas to represent the conductances due to ion precipitation, using a similar fitting process as what Vickrey et al (1981) and Robinson et al (1987) did.…”