REGO (Red-line Emission Geospace Observatory) and THEMIS (Time History of Events and Macroscale Interactions during Substorms) ASI (All-Sky Imager) images showing a double-arc. Credit: Liang et al. [2019], Figure 7e
Source: Journal of Geophysical Research: Space Physics

Few studies have yet explicitly connected observed auroral forms to satellite measurements of the precipitating particles and fields. In particular, Liang et al. [2019] have now distinguished the red line and green line aurora, which is new and noteworthy. This identification provides direct evidence that the lower-energy electrons associated with broadband (or Alfvenic) acceleration preferentially produce red-line emission.

With these joint optical and e-POP (Enhanced-Polar-Outflow-Probe) particle observations of Alfvenic auroras, the authors show that the 630 nm red-line auroras evolve distinctly from those seen on other optical instruments and are associated with low-energy precipitation bursts. These precipitation bursts are often the result of suprathermal electron bursts, which are characterized by a broad energy spectrum and a field-aligned pitch angle distribution.

Citation: Liang, J., Shen, Y., Knudsen, D., Spanswick, E., Burchill, J., & Donovan, E. [2019]. e‐POP and red line optical observations of Alfvénic auroras. Journal of Geophysical Research: Space Physics, 124.

—Viviane Pierrard, Editor, JGR: Space Physics

Text © 2019. The authors. CC BY-NC-ND 3.0
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