Near‐Sun and near‐Earth manifestations of solar eruptions

TLDR

The study explains the relationship among metric, decameter‑hectometric, and kilometric type II bursts using the fast‑mode magnetosonic speed profile in the solar atmosphere. The authors performed a two‑way correlation study of solar eruptions from 1994‑1998, comparing near‑Sun signatures (white‑light CMEs, metric type II bursts, EUV waves) with near‑Earth interplanetary signatures (decameter‑hectometric and kilometric type II bursts, ejecta, shocks) using Wind, SOHO, and ground‑based data. Most metric type II bursts (93%) lacked interplanetary signatures, and most IP events (80%) lacked metric counterparts; about a quarter of IP shocks were detected without drivers, indicating that shocks can extend beyond their CME drivers, with limb‑originating shocks reaching Earth and showing strong type II radio associations.

Abstract

We compare the near‐Sun and near‐Earth manifestations of solar eruptions that occurred during November 1994 to June 1998. We compared white‐light coronal mass ejections, metric type II radio bursts, and extreme ultraviolet wave transients (near the Sun) with interplanetary (IP) signatures such as decameter‐hectometric type II bursts, kilometric type II bursts, IP ejecta, and IP shocks. We did a two‐way correlation study to (1) look for counterparts of metric type II bursts that occurred close to the central meridian and (2) look for solar counterparts of IP shocks and IP ejecta. We used data from Wind and Solar and Heliospheric Observatory missions along with metric radio burst data from ground‐based solar observatories. Analysis shows that (1) most (93%) of the metric type II bursts did not have IP signatures, (2) most (80%) of the IP events (IP ejecta and shocks) did not have metric counterparts, and (3) a significant fraction (26%) of IP shocks were detected in situ without drivers. In all these cases the drivers (the coronal mass ejections) were ejected transverse to the Sun‐Earth line, suggesting that the shocks have a much larger extent than the drivers. Shocks originating from both limbs of the Sun arrived at Earth, contradicting earlier claims that shocks from the west limb do not reach Earth. These shocks also had good type II radio burst association. We provide an explanation for the observed relation between metric, decameter‐hectometric, and kilometric type II bursts based on the fast mode magnetosonic speed profile in the solar atmosphere.