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| Titel |
Connecting speeds, directions and arrival times of 22 coronal mass ejections from the Sun to 1 AU |
| VerfasserIn |
Christian Möstl, Keshav Amla, Jeff R. Hall, Paulett C. Liewer, Eric M. DeJong, Robin C. Colaninno, Astrid M. Veronig, Tanja Rollett, Manuela Temmer, Vanessa Peinhart, Jackie A. Davies, Noe Lugaz, Ying Liu, Charles J. Farrugia, Janet G. Luhmann, Bojan Vršnak, Richard A. Harrison, Antoinette B. Galvin |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250087695
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| Publikation (Nr.) |
 EGU/EGU2014-1755.pdf |
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| Zusammenfassung |
| Forecasting in situ properties of coronal mass ejections (CMEs) from remote images is
expected to strongly enhance predictions of space weather, and is of general interest for
studying the interaction of the solar wind with planetary environments. We study the
feasibility of using a heliospheric imager (HI) instrument, which is able to image the solar
wind density along the full Sun to 1 AU distance, for connecting remote images to in situ
observations of CMEs. Such an instrument is currently in operation on each of the two
STEREO spacecraft. We compare the predictions for speed and arrival time for
22 different CME events (between 2008-2012), each observed remotely by one
STEREO spacecraft, to the interplanetary coronal mass ejection (ICME) speed and
arrival time observed at in situ observatories (STEREO PLASTIC/IMPACT, Wind
SWE/MFI). We use croissant modeling for STEREO/COR2, and with a single-spacecraft
STEREO/HI instrument, we track each CME to 34.9 ± 7.1 degree elongation from the Sun
with J-maps constructed with the SATPLOT tool. We then fit geometrical models
to each track, assuming different CME front shapes (Fixed-Φ, Harmonic Mean,
Self-Similar Expansion), and constant CME speed and direction. We find no significant
preference in the predictive capability for any of the three geometrical modeling
methods used on the full event list, consisting of front- and backsided, slow and
fast CMEs (up to 2700 kms-1). The absolute difference between predicted and
observed ICME arrival times is 8.1 ± 6.4hours (rms value of 10.9h), and speeds are
consistent within 284 ± 291 kms-1, including the geometric effects of CME apex
or flank encounters. We derive new empirical corrections to the imaging results,
enhancing the performance of the arrival time predictions to 6.1 ± 5.0hours (rms
value of 7.9h), and the speed predictions to 53 ± 50 kms-1, for this particular
set of events. The prediction lead time is around 1 day (-26.4 ± 15.3h). CME
directions given by the HI methods differ considerably, and biases are found on
the order of 30-50 degree in heliospheric longitude, consistent with theoretical
expectations. These results are of interest concerning future missions such as Solar
Orbiter or a dedicated space weather mission positioned remotely from the Earth. |
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