A new class of complex ejecta resulting fromthe interaction of two CMEs and its expected geoeffectiveness


A significant portion of transients measured by spacecraft at 1 AU does not show the well-defined properties of magnetic clouds (MCs). Here we propose a new class of complex, non-MC ejecta resulting from the interaction of two coronal mass ejections (CMEs) with different orientations, which differ from previously studied multiple-MC events. At 1 AU, they are associated with a smooth rotation of the magnetic field vector over an extended duration and do not exhibit clear signs of interaction. We determine the characteristics of such events based on a numerical simulation and identify and analyze a potential case in the long-duration transient event measured in situ on 19–22 March 2001. Such events may result in intense, long-duration geomagnetic storms, with a sequence sawtooth events, and may sometimes be misidentified as isolated CMEs.

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Geophysical Research Letters



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