  The spatial inhomogeneity of the distribution of coronal mass ejection (CME)
occurrences in the solar atmosphere could provide a tool to estimate the
longitudinal position of the most probable CME-capable active regions in the
Sun. The anomaly in the longitudinal distribution of active regions themselves
is often referred to as active longitude (AL). In order to reveal the
connection between the AL and CME spatial occurrences, here we investigate the
morphological properties of active regions. The first morphological property
studied is the separateness parameter, which is able to characterize the
probability of the occurrence of an energetic event, such as a solar flare or
CME. The second morphological property is the sunspot tilt angle. The tilt
angle of sunspot groups allows us to estimate the helicity of active regions.
The increased helicity leads to a more complex buildup of the magnetic
structure and also can cause CME eruption. We found that the most complex
active regions appear near the AL and that the AL itself is associated with the
most tilted active regions. Therefore, the number of CME occurrences is higher
within the AL. The origin of the fast CMEs is also found to be associated with
this region. We concluded that the source of the most probably CME-capable
active regions is at the AL. By applying this method, we can potentially
forecast a flare and/or CME source several Carrington rotations in advance.
This finding also provides new information for solar dynamo modeling.
