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arXiv · 2502.18692

Streamer-like red line diffuse auroras driven by time domain structures and ECH waves associated with a plasma injection and braking ion flows

Yangyang Shen·Xu Zhang·Jun Liang·Anton Artemyev·Vassilis Angelopoulos·Emma Spanswick·Larry Lyons·Yukitoshi Nishimura
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Abstract

Auroral streamers are important meso-scale processes of dynamic magnetosphere-ionosphere coupling, typically studied using imagers sensitive to energetic (>1 keV) electron precipitation, such as all-sky imagers (ASIs). This paper reports streamer-like red-line auroras, representing low-energy (<1 keV) precipitation, observed poleward of a black aurora and an auroral torch. These red-line auroras were associated with a magnetospheric electron injection and braking ion flows. Observations were made using the THEMIS spacecraft and ground-based imagers, including the ASI, REGO, and meridian scanning photometer (MSP) at Fort Smith. We identify plasma sheet electron pitch-angle scattering by time-domain structures (TDSs) and electron cyclotron harmonics (ECH) waves as the driver of these red-line auroras, because of (1) a strong correlation (~0.9) between observed red-line intensities and precipitating fluxes; (2) consistent red-line intensities from auroral transport code forward modeling, and (3) consistent precipitation characteristic energies from MSP optical inference and quasi-linear estimates.

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Yangyang Shen, Xu Zhang, Jun Liang, Anton Artemyev, Vassilis Angelopoulos, Emma Spanswick, Larry Lyons, Yukitoshi Nishimura. 2025-02-25. Streamer-like red line diffuse auroras driven by time domain structures and ECH waves associated with a plasma injection and braking ion flows. https://arxiv.org/abs/2502.18692

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