等离子体层波粒相互作用及其电离层效应研究

发布时间：2018-04-03 07:21

本文选题：电磁离子回旋波　切入点：ELF嘶声　出处：《武汉大学》2016年博士论文

【摘要】：内磁层波粒相互作用导致高能粒子沉降是内磁层-电离层系统的主要物质耦合机制。等离子体层中波粒相互作用的特征及其相应的电离层效应是内磁层-电离层耦合研究的核心课题。本文主要围绕这一研究课题开展工作。首先,本文利用磁暴期间多颗卫星与地面的联合观测,研究等离子体层羽状结构(Plume)中波粒相互作用的特性。首次揭示了等离子体层Plume中等离子体波的空间分布：ELF嘶声(Hiss)位于Plume中电子密度的峰值附近,而EMIC波(Electromagnetic Ion Cyclotron Waves)位于Plume的外边界。获得了等离子体层Plume中环电流离子被EMIC波散射到损失锥的卫星实地观测证据。揭示了暴时亚极光区沉降的高能质子和电子的通量峰值在纬度上分离是由于等离子体层Plume区波粒相互作用的结果。其次,本文基于Cluster卫星穿越等离子体片进入内磁层的观测,研究高能离子散射到损失锥的物理机制。揭示了等离子体片及等离子体层Plume区高能离子被散射进入损失锥的不同物理机制：在磁尾等离子体片中归结于磁场的曲率散射机制；而在等离子体层Plume区则由EMIC波通过波粒相互作用而散射。最后,本文通过卫星与地面的联合观测,研究磁暴期间等离子体层波粒相互作用的电离层效应。首次获得EMIC波导致的离子沉降对电离层影响的观测证据。研究结果表明：暴时EMIC波导致的高能离子沉降能够引起亚极光区电离层E区峰值电子浓度及电导率显著增强。另外,我们发现了在磁暴期间等离子体层Plume中波粒相互作用导致的沉降粒子在电离层探测中的观测印记：等离子体层Plume中的Hiss散射的环电流电子能够沉降到电离层D区,导致暴时密度增强区(Storm Enhanced Density,即SED)测高仪观测的低频段电波被强烈吸收；而EMIC波散射的环电流离子沉降到电离层E区,导致了Es层的出现。本文的研究成果对于揭示内磁层-电离层系统的物质耦合特征及亚极光区的电离层观测研究具有重要的意义。
[Abstract]:The internal magnetospheric wave-particle interaction leads to the deposition of high-energy particles, which is the main material coupling mechanism of the inner magnetospheric and ionospheric system.The characteristics of wave-particle interaction in the plasma layer and the corresponding ionospheric effects are the core issues in the study of the internal magnetosphere-ionospheric coupling.This paper mainly focuses on this research topic.Firstly, the characteristics of wave particle interaction in plasma-plume structure (Plume) are studied by using the joint observations of several satellites and the ground during a magnetic storm.It is revealed for the first time that the spatial distribution of plasma waves in plasma layer Plume lies near the peak of electron density in Plume, while the EMIC wave is located at the outer boundary of Plume.Satellite field observations of the plasma layer Plume ring current ion scattering by EMIC waves to the loss cone are obtained.It is revealed that the peak flux of high energy protons and electrons deposited in the subauroral region during storms is separated at latitude due to the interaction of wave particles in the Plume region of the plasma layer.Secondly, the physical mechanism of high energy ion scattering to the loss cone is studied based on the observation of the Cluster satellite entering the inner magnetosphere through the plasma sheet.The different physical mechanisms of high energy ions scattering into the loss cone in plasma sheet and plasma layer in Plume region are revealed: the curvature scattering mechanism of magnetic field in magnetotail plasma sheet;In the Plume region of the plasma layer, the EMIC waves are scattered by the interaction of the waves and particles.Finally, the ionospheric effect of plasma-layer wave-particle interaction during magnetic storms is studied by satellite and ground observations.For the first time, observational evidence of the ionospheric effects of ion deposition induced by EMIC waves has been obtained.The results show that the high energy ion deposition caused by EMIC waves during storms can significantly increase the peak electron concentration and conductivity in the E region of the subaurora.In addition, we have found the observed imprint of particles deposited in the ionospheric sounding due to the interaction of particles in the plasma layer Plume during a magnetic storm: the ring current electrons scattered by the Hiss in the plasma layer Plume can be deposited into the ionospheric D region.The low-frequency radio waves observed by the SED altimeter are strongly absorbed, while the ring current ions of the EMIC wave are deposited into the E region of the ionosphere, which leads to the emergence of the es layer.The research results in this paper are of great significance to reveal the material coupling characteristics of the inner magnetosphere-ionospheric system and the ionospheric observation in the sub-auroral region.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P354;P353

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