Abstract:

Recent results based on optical auroral observations at Yellow River Station are reviewed. A systematic study of dayside diffuse aurora has important implications for many topics, such as generation and distribution of cold plasmas in the dayside outer magnetosphere, and penetration of magnetosheath particles into the magnetosphere. We report a new auroral form, the “throat aurora”, and confirm it corresponds to localized magnetopause indentation using coordinated satellite and ground observations. The occurrence rate of throat aurora can be high, and the special scale of magnetopause indentation associated with it as large as 2–3 RE. We suggest that throat auroras are likely caused by a magnetosheath high-speed jet impacting on the magnetopause, and that they should be associated with magnetopause reconnection. We confirm that a special diffuse aurora can be generated from magnetosheath particle penetration into the magnetosphere associated with generation of throat aurora. We propose that transient structures locally generated in the magnetosheath (but not originating from solar wind) frequently cause indentations in the subsolar magnetopause, trigger reconnection, result in series of responses in geospace, and accordingly play an important role in solar wind-magnetosphere coupling.

Key words: aurora, dayside diffuse aurora, throat aurora