Although this overall picture is well understood, with a few exceptions ( 3), it remains remarkably difficult to attribute observable auroral features to specific ionospheric signatures and magnetospheric processes. During the increased energy input from the solar wind, the auroral oval broadens and moves equatorward ( 2). This annulus is located at high latitudes, ~65° to 80° in magnetic latitude (MLAT), and is generally less than 10° in latitudinal width ( 1). At a global scale, the auroral regions form a large oval around the magnetic poles. This collisional process stochastically transfers energy to atmospheric atoms that later release the energy through a fluorescent emission of photons. These, in turn, accelerate and precipitate charged particles into the upper level of our atmosphere where they collide with its constituent gases. A brief description is that the interaction of the solar wind with Earth’s magnetic field generates strong electrical currents in Earth’s magnetosphere. The aurora borealis and aurora australis (commonly known as the northern and southern lights) are the multiscale end result of a complex chain reaction that begins at the sun and is governed by Earth’s magnetic and electric fields. On the basis of the measured ion properties and original citizen science name, we propose to identify this arc as a Strong Thermal Emission Velocity Enhancement (STEVE). These early results suggest the arc is an optical manifestation of SAID, presenting new opportunities for investigation of the dynamic SAID signatures from the ground. Observations from the Swarm satellite as it crossed the arc have revealed an unusual level of electron temperature enhancement and density depletion, along with a strong westward ion flow, indicating that a pronounced subauroral ion drift (SAID) is associated with this structure. Amateur photo sequences showed colors distinctly different from common types of aurora and occasionally indicated magnetic field–aligned substructures. This narrow, subauroral, visible structure, distinct from the traditional auroral oval, was largely undocumented in the scientific literature and little was known about its formation. A glowing ribbon of purple light running east-west in the night sky has recently been observed by citizen scientists.
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