A comparison of coronal mass ejections identified by manual and automatic methods

Abstract. Coronal mass ejections (CMEs) are related to many phenomena (e.g. flares, solar energetic particles, geomagnetic storms), thus compiling of event catalogs is important for a global understanding these phenomena. CMEs have been identified manually for a long time, but in the SOHO era, automatic identification methods are being developed. In order to clarify the advantage and disadvantage of the manual and automatic CME catalogs, we examined the distributions of CME properties listed in the CDAW (manual) and CACTus (automatic) catalogs. Both catalogs have a good agreement on the wide CMEs (width>120°) in their properties, while there is a significant discrepancy on the narrow CMEs (width≤30°): CACTus has a larger number of narrow CMEs than CDAW. We carried out an event-by-event examination of a sample of events and found that the CDAW catalog have missed many narrow CMEs during the solar maximum. Another significant discrepancy was found on the fast CMEs (speed>1000 km/s): the majority of the fast CDAW CMEs are wide and originate from low latitudes, while the fast CACTus CMEs are narrow and originate from all latitudes. Event-by-event examination of a sample of events suggests that CACTus has a problem on the detection of the fast CMEs.