本文综述了不同类型电离层场向电流(亦称为Birkeland电流)及其在地磁扰动(磁暴和亚暴)期间的时空分布特征.首先简述了场向电流近70年的研究历程,总结了各种与太阳风—行星际磁场(interplanetary magnetic field,IMF)、电离层电导率空间...本文综述了不同类型电离层场向电流(亦称为Birkeland电流)及其在地磁扰动(磁暴和亚暴)期间的时空分布特征.首先简述了场向电流近70年的研究历程,总结了各种与太阳风—行星际磁场(interplanetary magnetic field,IMF)、电离层电导率空间分布不均匀相关的1区和2区场向电流,北向、晨昏向IMF相关的场向电流,IMF Bx场向电流,电离层终端场向电流的典型分布特征及其研究进展.随后总结了磁暴期间场向电流的空间分布(即电流中心位置)、电流强度随磁暴相的时空变化规律,及其与太阳风—磁层耦合过程的关系.接着介绍了亚暴期间夜侧单、双电流楔模式、晨侧电流楔模式、电离层远程和局地闭合通道等几种不同的场向电流物理模型以及相关研究动态.最后,在此基础上展望未来,提出了几个尚待解决的科学问题.展开更多
We study the interaction between the Moon and the solar wind through a three-dimensional MHD simulation.Three cases have been discussed in which the interplanetary magnetic field lies at 90,180,and 135 to the solar wi...We study the interaction between the Moon and the solar wind through a three-dimensional MHD simulation.Three cases have been discussed in which the interplanetary magnetic field lies at 90,180,and 135 to the solar wind flow,respectively.A wake with low density and low pressure can always be formed behind the Moon.The plasma temperature and magnetic field are enhanced in the central wake,but the field strength is reduced in the surrounding region.A Mach cone is formed by rarefaction waves emanating from the limb.These rarefaction waves propagate via the fast magnetosonic mode with different velocities in different directions relative to the magnetic field.When the interplanetary magnetic field is not parallel to the solar wind flow,the wake shows some asymmetries,with an acceleration region turning up at the center.Finally,the results are compared with the observations by WIND spacecraft.Our calculations agree reasonably well with the observed values.展开更多
文摘本文综述了不同类型电离层场向电流(亦称为Birkeland电流)及其在地磁扰动(磁暴和亚暴)期间的时空分布特征.首先简述了场向电流近70年的研究历程,总结了各种与太阳风—行星际磁场(interplanetary magnetic field,IMF)、电离层电导率空间分布不均匀相关的1区和2区场向电流,北向、晨昏向IMF相关的场向电流,IMF Bx场向电流,电离层终端场向电流的典型分布特征及其研究进展.随后总结了磁暴期间场向电流的空间分布(即电流中心位置)、电流强度随磁暴相的时空变化规律,及其与太阳风—磁层耦合过程的关系.接着介绍了亚暴期间夜侧单、双电流楔模式、晨侧电流楔模式、电离层远程和局地闭合通道等几种不同的场向电流物理模型以及相关研究动态.最后,在此基础上展望未来,提出了几个尚待解决的科学问题.
基金supported by National Natural Science Foundation of China(Grant No.40974108)
文摘We study the interaction between the Moon and the solar wind through a three-dimensional MHD simulation.Three cases have been discussed in which the interplanetary magnetic field lies at 90,180,and 135 to the solar wind flow,respectively.A wake with low density and low pressure can always be formed behind the Moon.The plasma temperature and magnetic field are enhanced in the central wake,but the field strength is reduced in the surrounding region.A Mach cone is formed by rarefaction waves emanating from the limb.These rarefaction waves propagate via the fast magnetosonic mode with different velocities in different directions relative to the magnetic field.When the interplanetary magnetic field is not parallel to the solar wind flow,the wake shows some asymmetries,with an acceleration region turning up at the center.Finally,the results are compared with the observations by WIND spacecraft.Our calculations agree reasonably well with the observed values.
