1. 学术报告：Plasma Sheet O+ concentration impacts on the sawtooth/substorm events 时间：4月11日（周四）下午3点 地点：行政科研楼1514会议室 报告人：廖静  （博士） 单位：新罕布什尔大学 摘要：In order to study the relationship between sawtooth events and the plasma composition of the plasmasheet, we perform a detailed superposed epoch study of O+ concentration inside the near-Earth plasmasheet during sawtooth events and substorms sorted by different geomagnetic storm phases, using Cluster/CODIF data. The statistical results show that the O+ content increases during the sawtooth growth phase, regardless of the storm phase, reaches 20% around the dipolarization. During storm main phase, the plasma sheet O+ concentration during sawtooth events is only slightly higher than that observed during storm time substorm events. However, during storm recovery phase and non-storm times, there is significantly more O+ within the plasma sheet during sawtooth events than during storm time substorm events. No difference is found in the comparison between the O+/H+ density ratio changes during the first tooth in a series of sawtooth and the subsequent teeth. Hence, there is no evidence to support the hypothesis that subsequent teeth will lead to a closer near-Earth X-line due to the higher O+ inside the plasma sheet. Finally, despite the association between sawtooth events and high O+/H+ ratio, there are times when the O+/H+ density ratio is high in the plasma sheet but no sawtooth event is observed, and there are sawtooth events when the O+/H+ ratio is low.  This indicates that enhanced O+ is likely one of many factors that play a role in triggering the sawtooth events.

Qinxiu Li Posted at 2013-04-09 14:25 CST Last modified at 2013-04-09 14:25 CST Link to this poster Top