Prebreakup Arc Intensification due to Short Circuiting of Mesoscale Plasma Flows Over the Plasmapause

Abstract

The prebreakup arc at the inner edge of the auroral boundary is intensified upon arrival of an auroral streamer-the ionospheric signature of the earthbound mesoscale plasma flows (MPF). Yet the cause of electron precipitation enhancement only in this region remains unclear. We suggest that the intensified precipitation comes from the turbulent plasmasphere boundary layer (TPBL) that forms due to short circuiting of MPFs over the presubstorm plasmapause and overlaps with the plasma sheet (PS) inner boundary. Resonance interaction of the PS electrons with intense low-frequency plasma waves leads to enhanced precipitation from this narrow region. Indeed, the DMSP spacecraft observations near the substorm onset show intensified electron fluxes in a narrow region near the auroral boundary, which maps into the TPBL. The same pattern observed in conjunction with postonset auroral streamers points to the common mechanism, which is the short-circuiting process. Therefore, we suggest that the enhanced precipitation into the prebreakup arc is causally related to the MPFs' short circuiting over the plasmapause.We examine this problem using a concept of MPFs' short circuiting over the plasmapause (Mishin & Puhl-Quinn, 2007;Mishin et al., 2010Mishin, 2013) that explains the essential features of subauroral ion drifts (SAID). In this concept, low-ram pressure MPFs penetrate into the inner magnetosphe owing to the polarization field emerging at the forefront, as established in laboratory experiments (e.g., Brenning et al., 2005). This self-similar process breaks apart when the dense cold plasma at the presubstorm plasmapause shorts out the polarization charge. As a result, the MPF's (hot) electrons come to a halt hereby creating a steep, energy-independent PS/auroral boundary (cf. Newell & Meng, 1987), which is close to the prebreakup boundary owing to the steep density gradient at the plasmapause.The inflowing MPF's electrons pile up near the stopping point and create a narrow peak in the electron pressure, which creates the electron diamagnetic drift driving intense plasma turbulence (Mishin et al., 2010;Mishin & Sotnikov, 2017). Meanwhile, the MPF's ions move further inward until the nascent SAID electric field stops them. Thus, SAID inside of the plasmapause emerge just before the substorm breakup or pseudobreakup. Once created in the equatorial magnetosphere, the electric field propagates along the magnetic field into the ionosphere. That is, the plasmapause works as a power plant converting via short-circuiting the kinetic energy of MPFs into subauroral electromagnetic energy (Streltsov & Mishin, 2018).Most important for the purpose of this paper is that intense plasma waves develop in a narrow boundary layer (TPBL) enclosing the plasmapause around the MPF's stopping point (Mishin et al., 2010;Mishin, 2013). The TPBL overlaps with the PS inner edge, thence resonance wave-particle interactions cause enhanced precipitation into the prebreakup arc. This assumption is investigated in the rest of this paper using selected DMSP

Investigating the Coupled Magnetosphere‐Ionosphere‐Thermosphere (M‐I‐T) System's Responses to the 20 November 2003 Superstorm

“…As marked, ↓R2 and ↑R2 FACs flew into the duskside and dawnside subauroral regions respectively. Demanded by the SCW2L system, the SAPS flows developed (Mishin & Streltsov, 2020, 2021), as these R2 FACs connected with their respective oppositely directed R1 FACs at the equatorward edge of their adjacent auroral zones via Pedersen currents (J P ) flowing poleward on the duskside and equatorward on the dawnside.…”

“…Thus, the SAPS FC follows the development of the SCW2L system (Mishin et al., 2017), develops inside the regime of enhanced ↓R2 FACs, and is associated with ring current injections (Mishin, 2016). More recent studies show that the SAEF and therefore the SAPS flows are inherent in the SCW2L system and are created together with the SCW2L system, near the WTS (and near the Harang region), as the SCW2L system demands the closure of R1‐R2 FACs via meridional currents (Mishin & Streltsov, 2020, 2021). According to the statistical study of Foster and Vo (2002), the magnetic‐activity‐dependent SAPS can be maintained from dusk through midnight to dawn (in MLT), when Kp ≥ 5, as long as the R2 FACs flow in and out of the ionosphere at dusk (↓R2) and dawn (↑R2) respectively (Foster & Burke, 2002).…”

“…Another interesting feature of the NH-SH conjugate duskside and dawnside SAPS events is the equatorward-poleward expansion of the duskside and dawnside auroral zones. While the duskside SAPS development is well-known related to the activation of the SCW2L system (Mishin & Streltsov, 2020, 2021 and can be explained with the WTS (i.e., ionospheric signature of duskside auroral bulge) leading to duskside SAPS development, the dawnside auroral events and their relations to dawnside SAPS development are less understood. Based on the aurora and Harang region investigations of Lyons et al (2005) and on the duskside SAPS scenario of Mishin et al (2017), we provided observational evidence and explained the duskside (∼18 MLT) and dawnside (∼6 MLT) SAPS development.…”

Investigating the Development of Distinctive Subauroral Flow Channels During the November 7–8, 2004 Superstorm

“…The HR region is the ionospheric signature of the SCW (Haerendel, 2011) and is where the most intense Magnetosphere‐Ionosphere (M‐I) coupling occurs (Marghitu et al., 2009). While SAID forms before SCW activation, SAPS follows the development of the SCW (Mishin & Streltsov, 2020). SCW activation is followed by the rapid increase of energetic particle fluxes associated with the process of magnetic field dipolarization.…”

Complex Sub‐Auroral Flow Channel Structure Formed by Double‐Peak Sub‐Auroral Ion Drifts (DSAID) and Abnormal Sub‐Auroral Ion Drifts (ASAID)

“…But during intense storms, containing multiple substorms, the newly developed SAID FC can coexist with the earlier developed SAPS FC. Thus, the SAID FC can appear inside the SAPS FC since new plasma flows from the reconnection region can propagate under some angle to the midnight meridian, as the auroral boundary moves equatorward (E. Mishin et al., 2017; E. Mishin & Streltsov, 2020).…”