Which CME cone type is closer to observations?

Recently, CME cone models are widely used for inferring three dimensional structures of CMEs and their propagation through the heliosphere, especially for the input parameters of CME propagation models. However, there has been no observational test which cone type is closer to observations. In this study, we investigate which cone model is proper for halo CME morphology using 33 CMEs which are identified as halo CMEs by one spacecraft and as limb CMEs by the other ones. These CMEs were taken by SOHO/LASCO and STEREO/SECCHI during the period from 2010 December to 2011 June when two spacecraft were separated by 90±10 degrees, which allow us to directly estimate their angular widths from observations. From geometrical parameters of these CMEs such as their front curvature, they are classified into two groups: shallow cone CMEs (5 events), whose curvature radius is equal to the distance of CME front from the center of the Sun, and near full-cone CMEs (28 events), whose front has a semi-circle shape. Noting that the previous cone models are based on flat cone or shallow cone shapes, our results imply that a cone model based on the full cone shape should be developed.