Extreme geomagnetic disturbances due to shocks within CMEs

Author
Keywords
Abstract
We report on features of solar wind-magnetosphere coupling elicited by shocks propagating through coronal mass ejections (CMEs) by analyzing the intense geomagnetic storm of 6 August 1998. During this event, the dynamic pressure enhancement at the shock combined with a simultaneous increase in the southward component of the magnetic field resulted in a large earthward retreat of Earth\textquoterights magnetopause, which remained close to geosynchronous orbit for more than 4 h. This occurred despite the fact that both shock and CME were weak and relatively slow. Another similar example of a weak shock inside a slow CME resulting in an intense geomagnetic storm is the 30 September 2012 event, which strongly depleted the outer radiation belt. We discuss the potential of shocks inside CMEs to cause large geomagnetic effects at Earth, including magnetopause shadowing.
Year of Publication
2015
Journal
Geophysical Research Letters
Date Published
06/2015
URL
http://doi.wiley.com/10.1002/2015GL064530
DOI
10.1002/2015GL064530