学术论文

      第24太阳活动周地球附近磁云与非磁云事件的统计分析

      Statistical Comparison of Magnetic Clouds with Non-magnetic Clouds in Interplanetary Coronal Mass Ejections for Solar Cycle 24

      摘要:
      为研究第24太阳活动周中磁云(Magnetic Clouds,MC)与非磁云(Non-Magnetic Clouds,non-MC)的等离子体性质及其对空间天气的影响,使用1 AU处的观测数据对2008-2015年168个ICME事件进行统计与分析,其中认证出磁云事件68个,占总数的40.48%.通过分析磁云与非磁云等离子体参数对空间天气环境的影响及与太阳活动的关系,整体性质的对比及在第23和24太阳活动周中性质的对比,可以发现:在第24太阳周中,磁云引起的磁暴强度普遍大于非磁云,南北向磁场分量是引起磁暴的重要参数;磁云数和太阳黑子数有很好的相关性,非磁云数与行星际日冕物质抛射总数及黑子数的相关性稍弱,磁云数在太阳周的不同阶段表现出不同的分布特性;磁云的磁场强度和南向磁场分量整体强于非磁云,两者质子温度、密度等参数差异不大.第24周磁云事件引起的地磁效应整体上弱于第23周磁云事件,这与第24周磁云事件最大南向磁场分量、传播速度以及质子温度整体小于第23周磁云事件有关.
      Abstract:
      Interplanetary Coronal Massive Ejections (ICME) are major drivers of geo-magnetic storms and have great influence on the space weather environment.ICMEs can be divided into two parts:Magnetic Clouds (MC) and non-Magnetic Clouds (non-MC).MCs have large and smooth rotation in the magnetic fields' angle compared to non-MC,and they can interact with the Earth's magnetosphere more easily and cause severe space weather events.To make an insight into the ongoing Solar Cycle (Solar Cycle 24) and its MCs and non-MCs' characteristic and space weather effect,a statistical research is made on 168 ICMEs during 2008-2015 using the data from observation at 1AU.There are 68 MCs and the MC rate of ICME is 40.48%.The MCs and non-MCs' plasma parameters and their effect on the space weather,relationship with the solar activities,comparison with each other,and different appearance in Solar Cycle 23,24 were analyzed.In Solar Cycle 24,the geo-magnetic storms caused by MCs are usually stronger than those caused by non-MC.The south component of magnetic field is of great importance to cause the storms.MC occurrence has a good correlation with the Sunspot Number (SSN),while non-MC and ICME'correlation coefficient with SSN is smaller,and the number of MC shows different distributions during different solar cycle phases.MCs' magnetic field and south component of magnetic field are stronger than those of non-MC on total,but the difference between their temperature and proton density is very small.The geo-magnetic effect of MCs in Solar Cycle 24 are weaker than those in Solar Cycle 23.This is because of that the maximum south component of magnetic field,the propagation speed and the proton temperature of magnetic clouds in Solar Cycle 24 are smaller.
      作者: 娄飞 叶煜东
      Author: LOU Fei YE Yudong
      作者单位: 中国科学院国家空间科学中心 北京100190
      刊 名: 空间科学学报 ISTICPKU
      年,卷(期): 2017, 37(4)
      分类号: P353
      在线出版日期: 2017年8月30日