Statistical analysis of coronal shock dynamics implied by radio and white‐light observations

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Abstract
For 19 solar eruptive events we present a statistical comparison of the shock dynamics derived from the measured frequency drift rates of metric and decametric‐hectometric (D‐H) type II radio bursts with the dynamics of the associated coronal mass ejection (CME). We find that the shock speed parameters derived from the D‐H type II radio emissions generated in the high corona (∼2–4 R⊙; R⊙ = 696,000 km) are well correlated with the corresponding CME plane‐of‐the‐sky speeds (correlation coefficient = 0.71). On the other hand, we find no obvious correlation between the shock speed parameters derived from the metric type II radio bursts, generated in the middle corona (1.4–2 R⊙), and the corresponding CME speeds (correlation coefficient = −0.07). In general, we also find no clear correlation between the shock speed parameters derived from the metric type II bursts and the D‐H radio emissions (correlation coefficient = 0.3). However, the metric type II radio bursts sometimes include a second component that is possibly related to the D‐H radio emissions. These statistical comparisons of the shock dynamics, implied by the observed metric and D‐H type II frequency drift rates, provide further evidence for two distinct coronal shocks. Our statistical analyses are preceded by two specific examples that illustrate the methodology used in this study.