Ying D. Liu, Janet G. Luhmann, Christian Mostl, Juan C. Martinez-Oliveros, Stuart D. Bale, Robert P. Lin, Richard A. Harrison, Manuela Temmer, David F. Webb, Dusan Odstrcil
The successive coronal mass ejections (CMEs) from 2010 July 30 - August 1
present us the first opportunity to study CME-CME interactions with
unprecedented heliospheric imaging and in situ observations from multiple
vantage points. We describe two cases of CME interactions: merging of two CMEs
launched close in time and overtaking of a preceding CME by a shock wave. The
first two CMEs on August 1 interact close to the Sun and form a merged front,
which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle
imaging observations. Connections between imaging observations and in situ
signatures at 1 AU suggest that the merged front is a shock wave, followed by
two ejecta observed at Wind which seem to have already merged. In situ
measurements show that the CME from July 30 is being overtaken by the shock at
1 AU and is significantly compressed, accelerated and heated. The interaction
between the preceding ejecta and shock also results in variations in the shock
strength and structure on a global scale, as shown by widely separated in situ
measurements from Wind and STEREO B. These results indicate important
implications of CME-CME interactions for shock propagation, particle
acceleration and space weather forecasting.
View original:
http://arxiv.org/abs/1201.2968
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