Distribution of ULF Wave Power in Magnetic Latitude and Local Time Using THEMIS and Arase Measurements
Distribution of ULF Wave Power in Magnetic Latitude and Local Time Using THEMIS and Arase Measurements
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DOI：
10.1029/2022ja030469
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发表时间：
2022-10
期刊：
影响因子：
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通讯作者：
T. Sarris;Xinlin Li;Hong Zhao;K. Papadakis;Wenlong Liu;W. Tu;V. Angelopoulos;K. Glassmeier
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文献类型：
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作者：
T. Sarris;Xinlin Li;Hong Zhao;K. Papadakis;Wenlong Liu;W. Tu;V. Angelopoulos;K. Glassmeier
众所周知，超低频（ULF）波会在磁层中径向扩散数百keV到几MeV的电子，因为此类电子的漂移频率范围与波的频率重叠，从而导致共振相互作用。这一过程的理论框架是通过背景磁场中电子与环形和极向 ULF 波模式之间的共振相互作用的解析表达式来描述的。然而，大多数表达式根据从靠近赤道面的航天器或从地面获得的 ULF 波功率的估计来估计径向扩散率。在这项研究中，利用 THEMIS 和 Arase 任务的多年测量，我们对超低频波功率在磁纬度和当地时间的分布进行了统计分析，并表明磁场的径向和方位角分量的波功率随着远离磁赤道而增加。我们的结果可能对目前估计的径向扩散率产生重大影响。
Ultra‐low‐frequency (ULF) waves are known to radially diffuse hundreds‐keV to few‐MeV electrons in the magnetosphere, as the range of drift frequencies of such electrons overlaps with the frequencies of the waves, leading to resonant interactions. The theoretical framework for this process is described by analytic expressions of the resonant interactions between electrons and toroidal and poloidal ULF wave modes in a background magnetic field. However, most expressions estimate the radial diffusion rates based on estimates of the power of ULF waves that are obtained either from spacecraft close to the equatorial plane or from the ground. In this study, using multiyear measurements from the THEMIS and Arase missions, we present a statistical analysis of the distribution of ULF wave power in magnetic latitude and local time and show that the wave power of the radial and azimuthal components of the magnetic field increases away from the magnetic equator. Our result could have significant implications for the radial diffusion rates as currently estimated.