Comment on egusphere-2025-5536

Abstract. High spatial and temporal resolution images of red auroras over Germany during the 10–11 May 2024 magnetic storm have added new information concerning stable auroral red (SAR) arc formation. The high-altitude red aurora displayed brightness streaks/rays, which continued to lower altitude green auroral brightness rays, indicating that energetic electron precipitation along the Earth’s magnetic field lines are causing both auroras. Both the red and green auroras are diffuse in nature, indicating that instability of high-energy ring current particles inside the plasmasphere followed by wave-particle interactions is the most likely cause of the precipitating electrons. The 5577Å diffuse green aurora below the SAR arcs is a new scientific finding. This is named Stable Auroral Green (SAG) arcs. The SAR and SAG arc images were taken during the first and second steps of the 2024 superstorm. They occurred during intense substorms.