报告题目：Low frequency electromagnetic cyclotron waves in and around magnetic clouds: STEREO observations during 2007-2013

　　报告人：Guoqing Zhao（PhD, Luoyang Normal University）

　　摘要：Wave activities in the solar wind are an important topic and magnetic clouds (MCs) are a common phenomenon in interplanetary space, though waves activities associated with MCs have not been well documented. Based on a survey of 120 MCs observed by STEREO spacecraft during the years 2007–2013, this talk introduces electromagnetic cyclotron waves (ECWs) near the proton cyclotron frequency in and around MCs. For total 7807 ECW events, 24% of them occurred in the regions within MCs while 76% occurred in the regions around MCs. Statistics indicate that ECWs around MCs have higher frequencies, wider bandwidths, and stronger powers relative to the waves in MCs. More ECWs, on the other hand, tend to be related to a plasma with higher temperature, lower density, and larger velocity. In particular, it is found that there exist positive power law correlations between plasma betas and the wave frequencies, bandwidths, and powers. The results imply that the plasma beta should play an important role in determining the properties of ECWs, which is consistent with previous theory studies and the recent simulation results.

　　报告时间：2017年8月31日（周四）上午10:00-11:00

　　报告地点：紫台517会议室

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　　                                                       紫金山天文台学术委员会