Publication Date:
2018-01-05
Description:
After the passage of an interplanetary (IP) shock at 06:13UT on 24 August 2005, the enhancement (〉 6nPa) of solar wind dynamic pressure and the southward turning of interplanetary magnetic field (IMF) cause the earthward movement of dayside magnetopause and the drift loss of energetic particles near geosynchronous orbit. The persistent electron drift loss makes the geosynchronous satellites cannot observe the substorm injection electron phenomenon during the two substorm expansion phases (06:57 - 07:39UT) on that day. Behind the IP shock, the fluctuations (~ 0.5 – 3nPa) of solar wind dynamic pressure not only alter the dayside auroral brightness, but also cause the entire auroral oval to swing in the day-night direction. However, there is no Pi2 pulsation in the nightside auroral oval during the substorm growth phase from 06:13 to 06:57UT. During the subsequent two substorm expansion phases, the substorm expansion activities cause the nightside aurora oval brightening from substorm onset site to higher latitudes, and meanwhile, the enhancement (decline) of solar wind dynamic pressure makes the nightside auroral oval move towards the magnetic equator (the magnetic pole). These observations demonstrate that solar wind dynamic pressure changes and substorm expansion activities can jointly control the luminosity and location of the nightside auroral oval when the inner and external disturbances occur simultaneously. During extreme solar wind disturbances (e.g., the impact of a strong IP shock), the earthward movement of dayside magnetopause probably causes the disappearance of the substorm injection electrons near geosynchronous orbit.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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