On Aug 01, a series of solar events gave rise to a combination of Earth-directed halo CME's. We screen the event based on SDO and STEREO-Ahead movies, and ACE data.
What is peculiar is the fact that the accompagnied flare was only of a moderate class. It was a combination of different events in a fast sequence. In a way of speaking, all the energies involved in each process added to each other and resulted in a final energetic impact on Earth.
The August 01 event, triggered two Earth directed CME's. In a coronograph STEREOA/HI1, the second CME follows the first CME very close. One could even argue that there is only one CME: the second one overtook the first one. This is called CME cannibalism. The plasma structure can be followed in STEREOA/HI2 up to the arrival of a first shock at Earth on Aug 03 just before 17:00UT. This shock arrival is detected by ACE and visible in all solar wind parameters as a sudden jump. A second structure passed ACE on Aug 04 around 10:00UT. This magnetic structure could be eventually brought back to the second CME. In this case, the first CME was not completely eaten by the second one. The arrival of the CME's on Aug 03 and 04, triggered a minor storm and active conditions lasting up to Aug 05.
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| SDO/AIA 193 angstrom mpg-file |
SDO/AIA 304 angstrom mpg-file |
STEREO/COR2 white light mov-file |
| STEREO/HI1 white light mov-file |
STEREO/HI2 white light mov-file |
ACE solar wind data in situ Aug 01 - 05 |
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