Geoff Reeves and Colleagues Publish Study on Red Aurora in the Magnetosphere
Geoff Reeves and Colleagues Publish Study on Red Aurora in the Magnetosphere
Geoff Reeves, a senior scientist at Los Alamos National Laboratory and the New Mexico Consortium, has recently published a paper titled, Multi-Event Analysis of Plasma and Field Variations in Source of Stable Auroral Red (SAR) Arcs in Inner Magnetosphere During Non-Storm-Time Substorms, in the Journal of Geophysical Research: Space Physics.
Stable Auroral Red (SAR) arcs are a distinctive type of aurora that often appear during the recovery phase of magnetic storms and substorms. First discovered in the 1950s, these arcs appear red because of excited oxygen atoms in Earth’s upper atmosphere and are typically observed at latitudes slightly lower than the main auroral oval.
In this study, Reeves and his colleagues examined three SAR arc events using ground-based all-sky cameras and satellite observations from Arase and the Radiation Belt Storm Probes. For the first time, the team was able to evaluate three possible activation mechanisms for SAR arc formation using full-energy-range plasma and electromagnetic wave data.
The results suggest that Coulomb collisions are the most likely primary mechanism for generating SAR arcs, but they do not fully explain all observed events. The study also found that electromagnetic and electrostatic waves may contribute to SAR arc formation, and that SAR arcs can occur during non-storm-time substorms as well as during storm conditions.
These findings highlight the need for further research into SAR arc formation and the broader magnetosphere-thermosphere-ionosphere coupling processes that occur during both storm-time and non-storm-time substorms.
Read the entire article at:
Inaba, Y., K. Shiokawa, S. i. Oyama, Y. Otsuka, M. Connors, I. Schofield, Y. Miyoshi, S. Imajo, A. Shinbori, A. Y. Gololobov, Y. Kazama, S. Y. Wang, S. W. Y. Tam, T. F. Chang, B. J. Wang, K. Asamura, S. Yokota, S. Kasahara, K. Keika, T. Hori, A. Matsuoka, Y. Kasahara, A. Kumamoto, S. Matsuda, Y. Kasaba, F. Tsuchiya, M. Shoji, M. Kitahara, S. Nakamura, I. Shinohara, H. E. Spence, G. D. Reeves, R. J. Macdowall, C. W. Smith, J. R. Wygant, and J. W. Bonnell (2021), Multi-Event Analysis of Plasma and Field Variations in Source of Stable Auroral Red (SAR) Arcs in Inner Magnetosphere During Non-Storm-Time Substorms, Journal of Geophysical Research: Space Physics, 126, 4, doi:10.1029/2020ja029081.
Find the article online at: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JA029081
Above image taken from Figure 10 in the paper. The red dashed curves show the trajectory of the footprint of the Arase satellite. The red stars indicate the positions of the footprint of Arase when the image was taken. The horizontal and vertical axes correspond to the geographic longitude and latitude. The black dot at the center indicates the location of the ground based all-sky camera.
Article by Carrie Talus, NMC