Source Region of the Decameter - Hectometric Type II Radio Burst: Shock   - Streamer Interaction Region
  D-H type II radio bursts are widely thought to be caused by the coronal mass ejections (CMEs). However, it is still unclear where the exact source of the type IIs on the shock surface is. We identify the source regions of the decameter-hectometric (D--H) type IIs based on imaging observations from SOHO/LASCO and the radio dynamic spectrum from Wind/Waves. The analysis of two well-observed events suggests that the sources of these two events are located in the interaction regions between shocks and streamers, and that the shocks are enhanced significantly in these regions. 
Chenglong Shen, Chijian Liao, Yuming Wang, Pinzhong Ye, Shui Wang
astro-ph.SR