First Observation of a Type II Solar Radio Burst Transitioning between a Stationary and Drifting State

An effort to clarify how a meter-wave type II radio burst can appear not to propagate, describing a nice observation where both moving and stationary type-II-like signatures appeared. Historically the type II classification refers to the "slow drift" frequency variation, interpreted as a global shock wave driven to propagate faster than the Alfvén speed. But a shock can form in other contexts, such as in at the stagnation point of the reconnection outflow envisioned in the CSHKP cartoon. Note also the Delannee and Vainio-Khan cartoons for other variants on the basic type II interpretation.