Interplanetary shock induced ring current auroras

Abstract

On 21 January 2005, a fast interplanetary (IP) shock compressed the magnetosphere and caused detached auroras (DA) on the dayside, duskside and nightside ionosphere. The DA were detected by three independent FUV instruments: IMAGE/SI-12, TIMED/GUVI and DMSP/SSUSI. The SI-12 observations show that the dayside detached aurora (DDA) was located between 60° and 68° Mlat and between 06:00 and 15:00 MLT. It lasted for only ∼2 min. Coincident in situ Polar measurements show that sudden bursts of proton EMIC waves (∼2 min) were associated with the DDA. This provides direct evidence of the link between the EMIC waves and the DDA. The DA in the duskside and nightside appeared once the DDA disappeared. GUVI and SSUSI also observed the DA in the duskside and dayside with more details. Ring current simulations show that ∼10 keV protons with sausage-shaped spatial distribution of high anisotropy in flux and temperature were the particle source for the duskside and nightside DA. Compression of the magnetosphere appears to be the driver for both of the DDA and dusk/night DA. The nightside DA was observed for the first time during a sudden commencement. To unify the different terminologies, the detached auroras due to precipitating energetic protons from the ring current are called the ring current auroras. Copyright 2008 by the American Geophysical Union.