Citizen scientists are now providing true-color optical imagery using improved digital photography and crowdsourcing of auroral and related nighttime visual emissions. This has led to recent discoveries, for example, of STEVE (Strong Thermal Emission Velocity Enhancement) in the sub-auroral ionosphere arising from extreme ion drifts. Two visually distinct components are seen: a mauve or whitish arc extending in the magnetic east-west direction, and a region of green emission adjacent to the arc often described as a “picket fence”. High-resolution imagery analyzed by Semeter et al.  shows fine scale features within the green emission, consisting of narrow “streaks” that propagate toward STEVE from the poleward side, elongated along the direction of motion due to both motion blur and radiative lifetime. The emission seen is likely excited by strong electric fields responsible for ion drifts producing STEVE while generating ionospheric turbulence and superthermal electrons which produce the streaks reported here. A Viewpoint in this issue [Grandin 2020] gives more context for this result and reminds us to expect more discoveries coordinating citizen science observations!
Citation: Semeter, J., Hunnekuhl, M., MacDonald, E., Hirsch, M., Zeller, N., Chernenkoff, A. & Wang, J. . The Mysterious Green Streaks Below STEVE. AGU Advances, 1, e2020AV000183. . The Mysterious Green Streaks Below STEVE. AGU Advances, 1, e2020AV000183. https://doi.org/10.1029/2020AV000183
—Mary Hudson, Editor, AGU Advances