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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, A09S06, doi:10.1029/2004JA010926, 2005

October/November 2003 interplanetary coronal mass ejections: ACE/EPAM solar energetic particle observations

O. E. Malandraki

Space Research Laboratory, Democritus University of Thrace, Xanthi, Greece
Institute for Space Applications and Remote Sensing, National Observatory of Athens, Athens, Greece


D. Lario

Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA


L. J. Lanzerotti

Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey, USA


E. T. Sarris

Space Research Laboratory, Democritus University of Thrace, Xanthi, Greece


A. Geranios

Nuclear and Particle Physics Department, University of Athens, Athens, Greece


G. Tsiropoula

Institute for Space Applications and Remote Sensing, National Observatory of Athens, Athens, Greece


Abstract

In late October and early November 2003 the ACE spacecraft at 1 AU detected two shock-associated interplanetary coronal mass ejections (ICMEs). In the sheath region formed in front of both ICMEs, some of the highest speeds ever directly measured in the solar wind were observed. We analyze in detail the energetic particle signatures measured at 1 AU by the EPAM experiment on board ACE during the passage and in the vicinity of these ICMEs. Solar energetic particles (SEPs) are utilized as diagnostic tracers of the large-scale structure and topology of the interplanetary magnetic field (IMF) embedded within both ICME events. In order to explain the bidirectional particle flows observed within both ICMEs, we have examined two candidate scenarios for these ICMEs in terms of open and closed magnetic field configurations. In the context of an open field configuration, the enhanced magnetic field regions associated with the CME-driven shocks mirror the energetic particles and hence the observed bidirectional flows. In the context of a closed field configuration, bidirectional flows result from particle circulation and reflection in a looped field configuration. Furthermore, we use the ACE/EPAM observations to reassess the leading and trailing boundaries of the ICMEs with respect to those previously proposed based upon ACE/SWEPAM solar wind plasma, suprathermal electron measurements, and ACE/MAG magnetic field data.

Received 29 November 2004; accepted 21 April 2005; published 13 August 2005.

Keywords: interplanetary coronal mass ejections (ICMEs); solar energetic particle (SEPs); October/November 2003 events.

Index Terms: 2101 Interplanetary Physics: Coronal mass ejections (7513); 2114 Interplanetary Physics: Energetic particles (7514); 2134 Interplanetary Physics: Interplanetary magnetic fields; 2139 Interplanetary Physics: Interplanetary shocks; 2164 Interplanetary Physics: Solar wind plasma.

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Citation: Malandraki, O. E., D. Lario, L. J. Lanzerotti, E. T. Sarris, A. Geranios, and G. Tsiropoula (2005), October/November 2003 interplanetary coronal mass ejections: ACE/EPAM solar energetic particle observations, J. Geophys. Res., 110, A09S06, doi:10.1029/2004JA010926.