Statistical Correlations between Solar Microwave Bursts and Coronal Mass Ejections

Abstract

We compare listings of coronal mass ejections (CMEs) observed by LASCO on SOHO and solar microwave bursts (SMBs) recorded by the Radio Solar Telescope Network (RSTN) operated by the United States Air Force. These data sets are the product of stable and continuous observations of the whole Sun and provide suitable bases for robust statistical studies. In total, 3557 coronal ejections and nearly 1051 bursts above 50 sfu were observed from 1996 January through 2001 May. Correlated events are easily distinguished by time proximity. Correlations improve as CME launch heights are projected to the solar limb, when the rms scatter in CME-SMB delay was as little as 16 minutes, but because coronal disturbances are only visible when they emerge from behind occulting disks, timing associations depend on the assumed source and acceleration. The probability of correlation rises with burst flux, duration or temporal complexity, and ejection speed or width. For the 164 SMBs with intensities over 500 sfu, 70% ± 8% were associated with CMEs. For the 160 CMEs that were halo-like or have speeds over 1000 km s-1 (characteristics that have been associated with geoeffective events), 60% ± 8% and 84% ± 10% were associated with SMBs, respectively.