Wuppertal 2015 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 7: Sonne und Heliosphäre
EP 7.4: Vortrag
Donnerstag, 12. März 2015, 09:15–09:30, G.10.02 (HS 9)
Forbush decreases associated to Stealth Coronal Mass Ejections — •B Heber1, D. Galsdorf1, C. Herbst1, P. Kuehl1, C. Wallmann1, M. Dumbovic2, B. Vršnak2, A. Veronig3, M. Temmer3, C. Moestl3, and S. Dalla4 — 1Christian-Albrechts-Universität zu Kiel — 2Hvar Observatory, Faculty of Geodesy, University of Zagreb — 3Kačićeva 26, HR–10000 Zagreb, Croatia
3Institute of Physics/Kanzelhöhe Observatory, University of Graz, Austria — 4Jeremiah Horrocks Institute, University of Central Lancashire, Preston, PR1 2HE, UK
Interplanetary coronal mass ejections (ICMEs) are structures in the solar wind that are the counterparts of coronal mass ejections (CMEs) at the Sun. It is commonly believed that enhanced magnetic fields in interplanetary shocks and solar ejecta as well as the increased turbulence in the solar wind sheath region are the cause of Forbush decreases (FDs). Stealth CMEs i.e. CMEs with no apparent solar surface association have become a subject in recent studies of solar activity. Whether all of such stealth CMEs can drive a FD is difficult to investigate on the basis of neutron monitor NM measurements because these measurements not only reflect the GCR intensity variation in interplanetary space but also the variation of the geomagnetic field as well as the conditions in the Earth atmosphere. Single detector counter from spacecraft instrumentation exceed counting statistic of NMs allowing to determine intensity variation of less than 0.1% in interplanetary space. Here we present the ongoing analysis and a simple model that qualitatively describes the FDs associated to such MC.