Subaurorale

Subauroral refers to a region located at lower latitudes than the aurora borealis and aurora australis. It is situated roughly between 50 and 65 degrees magnetic latitude. While not directly experiencing the vibrant light displays of the aurora, the subauroral zone is influenced by the same geomagnetic activity that causes auroras. Particles from space, particularly electrons and protons, are guided by the Earth's magnetic field towards the polar regions. In the subauroral zone, these particles interact with the upper atmosphere, leading to various phenomena.

One significant characteristic of the subauroral region is the occurrence of subauroral ion drifts. These are large-scale, westward drifts of ions in the F-region of the ionosphere, particularly prominent during geomagnetic storms. These drifts can affect radio wave propagation and satellite communications. Another notable feature is the presence of the subauroral red arc (SAR arc), a faint, diffuse, and reddish-colored emission in the night sky. SAR arcs are typically observed equatorward of the auroral oval and are caused by the excitation of oxygen atoms by energetic electrons that have been transported from the magnetosphere. The subauroral zone plays a crucial role in understanding the dynamics of the Earth's magnetosphere and ionosphere and their interactions.