Naslov
Evolution of coronal mass ejections and the corresponding Forbush decreases: modelling vs. multi-spacecraft observations

Autori
Dumbović, Mateja ; Vršnak, Bojan ; Guo, J. ; Heber, B. ; Dissauer, K. ; Carcaboso-Morales, F. ; Temmer, M. ; Veronig, A. ; Podladchikova, T. ; Moestl, C. ; Amerstorfer, T. ; Kirin, Anamarija

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Fall Meeting abstracts / - , 2020, 1-1

Skup
Fall Meeting 2020

Mjesto i datum
Sjedinjene Američke Države, 01.12.2020. - 17.12.2020

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
coronal mass ejections ; flux ropes ; forbush decreases ; multi-spacecraft observations

Sažetak
One of the very common in situ signatures of interplanetary coronal mass ejections (ICMEs), as well as other interplanetary transients, are Forbush decreases (FDs), i.e. short-term reductions in the galactic cosmic ray (GCR) flux. A two-step FD is often regarded as a textbook example, which presumably owes its specific morphology to the fact that the measuring instrument passed through the ICME head-on, encountering first the shock front (if developed), then the sheath and finally the CME magnetic structure. The interaction of GCRs and the shock/sheath region, as well as the CME magnetic structure, occurs all the way from Sun to Earth, therefore, FDs are expected to reflect the evolutionary properties of CMEs and their sheaths. We apply modelling to different ICME regions in order to obtain a generic two- step FD profile, which qualitatively agrees with our current observation-based understanding of FDs. We next adapt the models for energy dependence to enable comparison with different GCR measurement instruments (as they measure in different particle energy ranges). We test these modelling efforts against a set of multi-spacecraft observations of the same event, using the Forbush decrease model for the expanding flux rope (ForbMod). We find a reasonable agreement of the ForbMod model for the GCR depression in the CME magnetic structure with multi-spacecraft measurements, indicating that modelled FDs reflect well the CME evolution.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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