Single‐Hemisphere Oxygen Outflow From Earth's Subauroral Zone

Abstract

Abstract Besides the cusp, polar cap, and auroral oval, the nightside subauroral zone has also recently been reported as a source region of the ionospheric oxygen outflows. However, the detailed mass and energy sources of these ions remain open questions. Here, we address this issue from the perspective of the response of conjugate hemispheres. Investigation of Van Allen Probes data demonstrates a notable preference of oxygen outflows from the nightside subauroral zone from the sunlit hemisphere. This characteristic eliminates the possibility of nightside auroral precipitation playing a significant role, as it is more prominent in darkness. Instead, it highlights sunlight‐induced ionization as the mass source and enhanced plasma waves from the magnetotail as the energy source. The results presented here further support the nightside subauroral zone as an independent source of magnetospheric oxygen ions.

Keywords

• ionospheric outlfows
• oxygen outflows
• subauroral region
• mass source of magnetosphere
• north‐south asymmetry
• seasonal variations