The Temporal and Spatial Behaviors of CME Occurrence Rate at Different Latitudes

Abstract

The statistical study of the coronal mass ejections (CMEs) is a hot topic in solar physics. To further reveal the temporal and spatial behaviors of the CMEs at different latitudes and heights, we analyzed the correlation and phase relationships between the occurrence rate of CMEs, the coronal brightness index (CBI), and the 10.7 cm solar radio flux (F10.7). We found that the occurrence rate of the CMEs correlates with the CBI relatively stronger at high latitudes (≥60°) than at low latitudes (≤50°). At low latitudes, the occurrence rate of the CMEs correlates relatively weaker with the CBI than the F10.7. There is a relatively stronger correlation relationship between CMEs, the F10.7, and the CBI during Solar Cycle 24 (SC24) than Solar Cycle 23 (SC23). During SC23, the high-latitude CME occurrence rate lags behind the F10.7 by 3 months, and during SC24, the low-latitude CME occurrence rate leads the low-latitude CBI by 1 month. The correlation coefficient values turn out to be larger when the very faint CMEs are removed from the samples of the CDAW catalog. Based on our results, we may speculate that the source regions of the high/low-latitude CMEs may vary in height, and the process of magnetic energy accumulation and dissipation is from the lower to the upper atmosphere of the Sun. The temporal offsets between different indicators could help us better understand the physical processes responsible for the solar-terrestrial interactions.