Abstract Seventy-one occurrences of coronal mass ejections (CMEs) associated with radio bursts, seemingly associated with type III bursts/fine structures (FSs), in the centimeter-metric frequency range during 2003-2005, were obtained with the spectrometers at the National Astronomical Observatories, Chinese Academy of Sciences (NAOC) and the Culgoora radio spectrometer and are presented. The statistical results of 68 out of 71 events associated with the radio type III bursts or FSs during the initiation or early stages of the CMEs indicate that most CMEs contain the emissions of radio type III bursts/FSs near the time of the CME's onset, in spite of their fast or slow speeds. Therefore, we propose that type III bursts and FSs are possible precursors of the onset of CMEs. We stress that the radio type III bursts/FSs in the centimeter-metric wavelength region and the CME transients possibly occurred in conjunction with the origin of the coronal precursor structures. Thus, the statistical results support the suggestions that type III bursts/FSs are indicators of extra energy input into the corona at the CMEs' onset, and that the type III bursts/FSs are produced primarily due to a coronal instability which eventually triggers the CME process. This may signify that the centimeter-metric radio bursts corresponding to or near the CME's onset are caused by the disturbed corona (possibly including minor magnetic reconnections).

Keywords Sun: radio burst — radio fine structure — coronal mass ejection

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