Type-II radio bursts are usually observed below 400 MHz with slowly-drifting narrow fundamental and/or harmonic bands. Events with starting frequencies higher than 400 MHz are rarely reported (e.g., Pohjolainen et al. 2008). Such high-frequency Type-IIs may stem from the CME interaction with surrounding dense structures in the corona, such as streamers, ray-like or loop structure, or from sources in the lower corona.
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