[P-EM13] Dynamics of the Inner Magnetospheric System

[PEM13-01] Diffuse aurora flashes and black aurora associated with the dayside plasmapause as caused by a solar wind pressure pulse

*片岡 龍峰¹、坂野井 健²、三好 由純³、田中 良昌¹、村瀬 清華¹、門倉 昭¹、細川 敬祐⁴、藤田 茂⁵ (1.国立極地研究所、2.東北大学、3.名古屋大学、4.電気通信大学、5.統計数理研究所)

キーワード：ブラックオーロラ、プラズマ圏界面、コーラス波動

We report a new type of black aurora which repeatedly appeared only when the diffuse aurora flashes over the whole sky. The black aurora event was identified in the afternoon sector (1300~1330 UT = 13~13.5 MLT) at Syowa Station in the Arctic during the solar wind pressure pulse event on July 7, 2023. Followings are our interpretation of the appearance of the diffuse flashes and black aurora: The solar wind pressure pulse caused the field line resonance to modulate the nonlinear wave growth of chorus waves around the plasmapause, which can scatter energetic electrons to emit the repeating diffuse aurora flashes propagating poleward across the whole field-of-view. The nonlinear wave growth is correlated with the high density of the energetic electrons, and the suppressed wave growth inside the plasmasphere appear as the black aurora.