Type II Radio Emission and Solar Energetic Particle Events

Abstract. Type II radio bursts, solar energetic particle (SEP) events, and interplanetary (IP) shocks all have a common cause, viz., fast and wide (speed ≥ 900 km/s and width ≥ 60o)) coronal mass ejections (CMEs). Deviations from this general picture are observed as (i) lack of type II bursts during many fast and wide CMEs and IP shocks, (ii) slow CMEs associated with type II bursts and SEP events, and (iii) lack of SEP events during many type II bursts. I examine the reasons for these deviations. I also show that ground level enhancement (GLE) events are consistent with shock acceleration because a type II burst is present in every event well before the release of GLE particles and SEPs at the Sun