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Coronal Magnetic Field Topology over Filament Channels: Implication for Coronal Mass Ejection Initiations

The magnetic field topology at the coronal mass ejection (CME) source regions has been one of the major focuses of CME initiation models. While the "breakout" model requires a quadrupolar magnetic topology in the solar corona to enable an eruption, other models have shown that a bipolar magnetic topology can be the source region of a CME. In this paper, we use observational data and a potential field source surface model to investigate the magnetic field topology over CME productive quiescent filaments. A total of 80 quiescent filament-associated CME events during 1996-2004, spanning almost one solar cycle, with angular width ≥80° are selected for this study. We found both bipolar topology and quadrupolar topology at CME source regions. This observational test of the assumptions of theoretical CME models suggests that bipolar topology is more common overall and in each year. The total occurrence ratio between quadrupolar and bipolar topology is about 1 : 3 with this selection of events. On the rising phase of the solar cycle, there is mostly bipolar topology, but on the declining phase, there is a mixture of both bipolar and quadrupolar topology. The bipolar topology occurrence has no clear solar cycle dependence. The quadrupolar topology occurrence peaks on the declining phase in the current solar cycle 23.