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The relative importance of different initiation mechanisms for coronal massejections (CMEs) on the Sun is uncertain. One possible mechanism is the loss ofequilibrium of coronal magnetic flux ropes formed gradually by large-scalesurface motions. In this paper, the locations of flux rope ejections in arecently-developed quasi-static global evolution model are compared withobserved CME source locations over a 4.5-month period in 1999. Using EUV data,the low-coronal source locations are determined unambiguously for 98 out of 330CMEs. Despite the incomplete observations, positive correlation (withcoefficient up to 0.49) is found between the distributions of observed andsimulated ejections, but only when binned into periods of one month or longer.This binning timescale corresponds to the time interval at which magnetogramdata are assimilated into the coronal simulations, and the correlation arisesprimarily from the large-scale surface magnetic field distribution; only a weakdependence is found on the magnetic helicity imparted to the emerging activeregions. The simulations are limited in two main ways: they produce fewerejections, and they do not reproduce the strong clustering of observed CMEsources into active regions. Due to this clustering, the horizontal gradient ofradial photospheric magnetic field is better correlated with the observed CMEsource distribution (coefficient 0.67). Our results suggest that, while thegradual formation of magnetic flux ropes over weeks can account for manyobserved CMEs, especially at higher latitudes, there exists a second class ofCMEs (at least half) for which dynamic active region flux emergence on shortertimescales must be the dominant factor.

Comparison of a Global Magnetic Evolution Model with Observations of Coronal Mass Ejections