[P-EM16] Heliosphere and Interplanetary Space

[PEM16-P05] Characteristics of spectral fine structures of metric type II radio bursts

*Hiroaki Misawa¹, Fuminori Tsuchiya¹, Yozi Kuwayama¹ (1.Planetary Plasma and Atmospheric Research Center, Graduate School of Science, Tohoku University)

Keywords:Sun, type II solar radio burst, spectral fine structure, solar energetic particle

It is well known that a type II burst is one of sporadic and intense solar non-thermal radio phenomena, which shows gradual negative frequency drift in the metric to kilometric wavelength ranges and is generated with a coronal mass ejection (CME) event. As a plausible generation process of type II bursts, it is proposed that electro-static plasma waves originated from energetic electrons are effectively converted to electro-magnetic waves (type II bursts) at the region where the local plasma frequency is equal to wave frequency. A type II burst often occurs with energetic protons and ions with the energy of more than the MeV grade, and such an energetic phenomena is called a solar energetic particle (SEP) event. The coincident occurrence of type II bursts and SEPs strongly suggests that both energetic electrons and protons/ions would be the same origin initiated by a CME event. The occurrence characteristics of type II radio bursts and also SEPs have important information on the origins and generation processes of energetic particles.

We have investigated the relationship between SPEs and metric type II bursts from a view point of the clarification of characteristics of SEPs from the occurrence characteristics of type II bursts. We have especially paid attention to spectral fine structures of type II bursts identified in the metric wavelength by using the high resolution spectro-polarimeter ‘AMATERAS’ (Iwai et al., 2012). In our presentation, we will introduce characteristics of the fine structures of type II bursts, especially their frequency dependent nature.