Wave-particle interactions play a fundamental role in the dynamic variability of Earth’s donut-shaped radiation belts that are highly populated by magnetically trapped energetic particles and characteristically separ...Wave-particle interactions play a fundamental role in the dynamic variability of Earth’s donut-shaped radiation belts that are highly populated by magnetically trapped energetic particles and characteristically separated by the slot devoid of high energetic electrons.Owing to the continuous accumulation of high-quality wave and particle measurements from multiple satellites in geospace,the important contribution of ground-based very-low-frequency(VLF)transmitter waves to the electron dynamics in the near-Earth space has been unprecedently advanced,in addition to those established findings of the significant effects of a variety of naturally occurring magnetospheric waves.This paper focuses on the artificial modification of Earth’s inner radiation belt and slot by artificial VLF transmitter emissions.We review the global distributions of VLF transmitter waves in geospace,their scattering effects on radiation belt electrons in terms of both theoretical and observational analyses,and diffusion simulation results of wave-particle interactions along with data-model comparisons.We start with a brief review of the radiation belt electron dynamics and an introduction of anthropogenic VLF transmitter waves.Subsequently,we review the global morphology of in situ VLF transmitter waves corresponding to different transmitter locations,including their day-night asymmetry,geographic distributions,seasonal and geomagnetic activity dependence,and wave propagation features.Existed theoretical and observational analyses of electron scattering effects by VLF transmitter waves are then reviewed to approach the underlying physics that can modulate the spatio-temporal variations of the electron radiation belts.Further Fokker-Planck electron diffusion simulations and their comparisons with realistic satellite observations clearly indicate that VLF transmitter emissions can effectively remove energetic electrons to produce a radially bifurcated electron belt,thereby quantitatively confirming the direct link between operations of VLF transmitters at ground and changes of the energetic electron environment in space.We finally discuss the unsolved problems and possible future research in this area,which has important implications for potential mitigation of the natural particle radiation environment with active means.展开更多
介绍了一套同时工作在甚高频(very high frequency,VHF)和甚低频/低频(very-low/low frequency,VLF/LF)频段的三维闪电定位系统,并给出了初步观测结果。系统使用到达时间差法对2个频段的闪电辐射源进行定位,能连续地给出雷暴过程中闪电...介绍了一套同时工作在甚高频(very high frequency,VHF)和甚低频/低频(very-low/low frequency,VLF/LF)频段的三维闪电定位系统,并给出了初步观测结果。系统使用到达时间差法对2个频段的闪电辐射源进行定位,能连续地给出雷暴过程中闪电活动空间位置,并详细给出单次闪电的发展路径,在使用2个频段辐射波形参数进行定位的同时还可以保存原始波形用于深入研究。VHF、VLF/LF 2个频段闪电定位结果的时间分辨率分别为100?s和1ms,定位精度在站网覆盖范围可优于200m。2个频段的定位结果都能很好地描述雷暴中的闪电活动,但表现出的特征有一定差异。两频段定位结果对单个闪电发生路径进行描绘时,VLF/LF频段的大部分定位结果能与VHF定位结果重叠。展开更多
利用短基线时间差甚高频（VHF）辐射源定位系统对一次多回击负地闪放电过程进行详细研究发现,负地闪的预击穿、梯级先导、直窜先导及回击后云内放电过程伴随有较强烈的VHF辐射.结合同步观测的闪电快、慢电场变化资料,分析VHF辐射源时空...利用短基线时间差甚高频（VHF）辐射源定位系统对一次多回击负地闪放电过程进行详细研究发现,负地闪的预击穿、梯级先导、直窜先导及回击后云内放电过程伴随有较强烈的VHF辐射.结合同步观测的闪电快、慢电场变化资料,分析VHF辐射源时空发展特征发现,预击穿阶段辐射源在云中的放电通道为双向发展,平均速度均在104 m s-1量级,预击穿下行分支直接转化为梯级先导,并产生多个分支通道同时向地面发展,先导平均速度在105 m s-1量级.继后回击之前先导过程均产生多个分支通道,直窜先导平均速度在105～106 m s-1量级,新开辟的梯级先导速度在105 m s-1量级.闪击间及地闪后期云内放电活动较为复杂,主要表现为辐射源从闪电起始区域发展,进一步延伸云内闪电通道.地闪后期多次负极性K变化过程（Kitagawa and Kobayashi,1958）主要表现为负极性流光沿之前的正极性电离通道快速发展,平均速度在106 m s-1量级.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42025404,42188101,41904144,41704162)the Fundamental Research Funds for the Central Universities(Grant Nos.2042021kf1045,2042021kf1056)+1 种基金the B-type Strategic Priority Program of the Chinese Academy of Sciences(Grant No.XDB41000000)the Pre-research projects on Civil Aerospace Technologies(Grant Nos.D020308,D020104&D020303).
文摘Wave-particle interactions play a fundamental role in the dynamic variability of Earth’s donut-shaped radiation belts that are highly populated by magnetically trapped energetic particles and characteristically separated by the slot devoid of high energetic electrons.Owing to the continuous accumulation of high-quality wave and particle measurements from multiple satellites in geospace,the important contribution of ground-based very-low-frequency(VLF)transmitter waves to the electron dynamics in the near-Earth space has been unprecedently advanced,in addition to those established findings of the significant effects of a variety of naturally occurring magnetospheric waves.This paper focuses on the artificial modification of Earth’s inner radiation belt and slot by artificial VLF transmitter emissions.We review the global distributions of VLF transmitter waves in geospace,their scattering effects on radiation belt electrons in terms of both theoretical and observational analyses,and diffusion simulation results of wave-particle interactions along with data-model comparisons.We start with a brief review of the radiation belt electron dynamics and an introduction of anthropogenic VLF transmitter waves.Subsequently,we review the global morphology of in situ VLF transmitter waves corresponding to different transmitter locations,including their day-night asymmetry,geographic distributions,seasonal and geomagnetic activity dependence,and wave propagation features.Existed theoretical and observational analyses of electron scattering effects by VLF transmitter waves are then reviewed to approach the underlying physics that can modulate the spatio-temporal variations of the electron radiation belts.Further Fokker-Planck electron diffusion simulations and their comparisons with realistic satellite observations clearly indicate that VLF transmitter emissions can effectively remove energetic electrons to produce a radially bifurcated electron belt,thereby quantitatively confirming the direct link between operations of VLF transmitters at ground and changes of the energetic electron environment in space.We finally discuss the unsolved problems and possible future research in this area,which has important implications for potential mitigation of the natural particle radiation environment with active means.
文摘介绍了一套同时工作在甚高频(very high frequency,VHF)和甚低频/低频(very-low/low frequency,VLF/LF)频段的三维闪电定位系统,并给出了初步观测结果。系统使用到达时间差法对2个频段的闪电辐射源进行定位,能连续地给出雷暴过程中闪电活动空间位置,并详细给出单次闪电的发展路径,在使用2个频段辐射波形参数进行定位的同时还可以保存原始波形用于深入研究。VHF、VLF/LF 2个频段闪电定位结果的时间分辨率分别为100?s和1ms,定位精度在站网覆盖范围可优于200m。2个频段的定位结果都能很好地描述雷暴中的闪电活动,但表现出的特征有一定差异。两频段定位结果对单个闪电发生路径进行描绘时,VLF/LF频段的大部分定位结果能与VHF定位结果重叠。
文摘利用短基线时间差甚高频（VHF）辐射源定位系统对一次多回击负地闪放电过程进行详细研究发现,负地闪的预击穿、梯级先导、直窜先导及回击后云内放电过程伴随有较强烈的VHF辐射.结合同步观测的闪电快、慢电场变化资料,分析VHF辐射源时空发展特征发现,预击穿阶段辐射源在云中的放电通道为双向发展,平均速度均在104 m s-1量级,预击穿下行分支直接转化为梯级先导,并产生多个分支通道同时向地面发展,先导平均速度在105 m s-1量级.继后回击之前先导过程均产生多个分支通道,直窜先导平均速度在105～106 m s-1量级,新开辟的梯级先导速度在105 m s-1量级.闪击间及地闪后期云内放电活动较为复杂,主要表现为辐射源从闪电起始区域发展,进一步延伸云内闪电通道.地闪后期多次负极性K变化过程（Kitagawa and Kobayashi,1958）主要表现为负极性流光沿之前的正极性电离通道快速发展,平均速度在106 m s-1量级.
