Variations in the Correlations of Acceleration and Force of Slow and Fast CMEs with Solar Activity during Solar Cycles 23 – 24

Abstract

Studying the behavior of coronal mass ejections (CMEs) is important for both solar physics and space weather. The correlations of smoothed monthly mean daily integrated CME acceleration [$a$], mass [$M$], and the force [$Ma$] to drive CMEs with sunspot activity [$R_{\mathrm{I}}$] are analyzed for both slow and fast CMEs and for both Solar Cycles 23 and 24 separately. It is found that $a$ is inversely related to both $R_{\mathrm{I}}$ and $M$. The correlation between $Ma$ and $R_{\mathrm{I}}$ for both slow and fast CMEs is negative at the rising phase of Solar Cycle 23 and positive otherwise. There is a sharp peak in $\gamma =Ma/R_{\mathrm{I}}$ near the solar minimum (December 2008) for both slow and fast CMEs. However, for fast CMEs, there is a sharp negative peak near the previous solar minimum (August 1996) and another positive peak near the current solar minimum (2019). The positive (negative) peak tends to be related to the solar minimum from a stronger (weaker) to a weaker (stronger) solar cycle. These results suggest that the CME acceleration depends more on the strength of solar activity than on the CME’s speed. Stronger magnetic activity may slow down the CMEs that are too massive or too fast and weaker activity may speed up the CMEs that are less massive or too slow. During a few years’ period of magnetic-field polarity reversal around the solar minimum, the force provided by large-scale magnetic-field structures may not be strong enough to constrain CME motions, leading to the “escape” of CMEs with large $|\gamma |$.