Título: Earth Coupling during May 27, 2017 magnetic storm: A Case Study on Unusual Stable Auroral Red (SAR) Arc Observed at King George Island 

Palestrante:  Prof. Dr. Cosme Alexandre Barros (UAF/UFCG)

http://lattes.cnpq.br/3927992223541417

 

Local e data: Auditório Jurgen Precker (UAF), 22 de setembro de 2026, às 16:00h.

Resumo: A Stable Auroral Red (SAR) arc observed during the geomagnetic storm of 27–28 May 2017 was investigated using OI 630.0 nm airglow measurements from an all-sky imager at the Brazilian Antarctic Station Comandante Ferraz (L ≈ 2.26). The SAR arc appeared at ~02:40 UT on 28 May, initially in the southern sector of the field of view, and progressively drifted equatorward toward the zenith before fading around 08:40 UT, consistent with typical storm-time subauroral red emissions. The event was associated with a type II coronal mass ejection (CME) detected on 23 May 2017 and its subsequent interplanetary counterpart (ICME), which reached the L1 point at 14:45 UT on 27 May and impacted Earth’s magnetosphere under sustained disturbed solar wind conditions. During the storm’s main phase, Van Allen Probe B recorded a pronounced dropout of 7–51 keV proton fluxes at L ≈ 2.4, concurrent with enhanced electromagnetic ion cyclotron (EMIC) wave activity. The temporal coincidence suggests that EMIC wave–particle interactions induced pitch-angle scattering and precipitation of ring current protons. This precipitation likely contributed to localized heating of the subauroral F region, enhancing the OI 630.0 nm emission and driving the formation of the SAR arc. Additionally, the results provide evidence of wave–particle coupling processes during geomagnetic disturbances, with proton precipitation potentially increasing E-region ionization, as indicated by the occurrence of auroral sporadic E (Esₐ) layers at high latitudes.