Global Penetration and Propagation Processes of Electromagnetic Disturbances from the Polar to the Equatorial Ionosphere

本研究的目的是了解从极地到赤道地区的大气过渡区（中性粒子和带电粒子混合的高度为80 ~ 5-600 Km的区域）的大规模电磁穿透和传播过程。利用wind和ISTP卫星的太阳风和粒子数据，我们明确了太阳风扰动的时空尺度与大尺度电磁扰动之间的关系，这些大尺度电磁扰动甚至可以穿透到赤道地区的地面。特别是通过对卫星和地面观测数据的综合分析，可以从理论上理解极地和赤道地区的电磁耦合过程，包括太阳风、磁层、电离层、大气和导电地球。(1)磁层瞬态响应的传播研究本研究通过对SI事件引起的地面磁场极化变化特征的研究，明确了与SC/SI事件相关的极地磁场变化只能用极地电离层中产生的涡旋流运动来解释。电离层涡旋流的运动包含磁层顶变形的信息。因此，目前的研究结果表明，通过地磁场变化监测整个磁层的瞬态响应是可能的。(2) ULF脉动的全球传播研究通过对环太平洋磁力计网（CPMN）站点磁资料的分析，可以得出地面观测到的π 2磁脉动至少由五个分量组成：(1)极光纬度的脉冲场向电流的弹跳模式，(2)亚风暴电流的楔状振荡模式，(3)等离子体顶的表面波模式，(4)磁层内部的腔状振荡模式，以及(5)Pi 2电场从极光纬度的夜侧向赤道日侧的传输模式。地面π 2脉动是这五种模式的集合，它们显示自己的传播（或定时）和空间照明。(3)电离层电场扰动研究为了研究电离层的电场扰动，我们在福冈SASAGURI （SASAGURI）安装了调频/连续波雷达，对电离层的变化进行了稳定观测。因此，我们可以成功地探测到由于施加在极电离层上的电场而引起的电离层的时空变化。这些观测结果表明，施加在极地电离层上的电场几乎同时向赤道地区传播。少

A purpose of this study is to understand a large-scale electromagnetic penetration and propagation process in the atmospheric transition region (the region from 80 to 5-600 Km in the height where neutral and charged particles are mixed in) from the polar to equatorial regions. By using the solar wind and particle data from the WIND and ISTP satellites, we clarified the relationships between the temporal and spatial scales of disturbances in the solar wind and the large-scale electromagnetic disturbances that can penetrate even into the equatorial region on the ground. Especially, in term of the composite data analysis from the satellites and ground-based observations, we can theoretically understand the electromagnetic coupling process between the polar and equatorial regions, including the solar wind, magnetosphere, ionosphere, atmosphere and conductive earth.(1) A study on a propagation of the transient response of the magnetosphereIn this study, by investigation of the characteristi … More cs of the polarization of magnetic variations on the ground due to the SI-event, we cleared that magnetic variations in the polar region associated with SC/SI events could be interpreted only by a motion of the vortex currents generated in the polar ionosphere. The motion of the ionosphere vortex current includes the information of the deformation of the magnetopause. Therefore, the present results suggest a possibility of the monitoring for the transient response of the whole magnetosphere from ground magnetic variations.(2) A study on a global propagation of the ULF pulsationsFrom analyses of magnetic data from the Circum-pan-Pacific Magnetometer Network (CPMN) stations, it can be concluded that Pi 2 magnetic pulsations observed on the ground consist of at least five components : (1) a bouncing mode of impulsive field-aligned current at the auroral latitude, (2) a substorm current wedge oscillation (3) a surface wave at the plasmapause, (4) a cavity-like oscillation in the inner magnetosphere, and (5) a transmission of the Pi 2 electric field from the nightside auroral latitude to the dayside equatorial region. The ground Pi 2 pulsations are an ensemble of these five modes, which show their own propagations (or timings) and spatial illuminations.(3) A study on the disturbance of the electric field in the ionosphereIn order to investigate the electric disturbances in the ionosphere, we installed the FM/CW radar at SASAGURI (Fukuoka City), and made steady observation of the variations of the ionosphere. As a result, we could successfully detect the temporal and spatial variations of the ionosphere due to the imposed electric field on the polar ionosphere. These observations reveal that the electric field imposed on the polar ionosphere spread event to the equatorial region almost simultaneously. Less