Correlations Between CME Parameters and Sunspot Activity

Abstract

Smoothed monthly mean coronal mass ejection (CME) parameters (speed, acceleration, central position angle, angular width, mass, and kinetic energy) for Cycle 23 are cross-analyzed, showing that there is a high correlation between most of them. The CME acceleration (a) is highly correlated with the reciprocal of its mass (M), with a correlation coefficient r=0.899. The force (Ma) to drive a CME is found to be well anti-correlated with the sunspot number (R z), r=−0.750. The relationships between CME parameters and R z can be well described by an integral response model with a decay time scale of about 11 months. The correlation coefficients of CME parameters with the reconstructed series based on this model ( $\overline{r}_{\mathrm{f1}}=0.886$ ) are higher than the linear correlation coefficients of the parameters with R z ( $\overline{r}_{\mathrm{0}}=0.830$ ). If a double decay integral response model is used (with two decay time scales of about 6 and 60 months), the correlations between CME parameters and R z improve ( $\overline{r}_{\mathrm{f2}}=0.906$ ). The time delays between CME parameters with respect to R z are also well predicted by this model (19/22=86%); the average time delays are 19 months for the reconstructed and 22 months for the original time series. The model implies that CMEs are related to the accumulation of solar magnetic energy. These relationships can help in understanding the mechanisms at work during the solar cycle.