Wave growth of electromagnetic ion cyclotron (EMIC) emissions observed in the outer magnetosphere is mainly controlled by compression events resulting from solar wind dynamic pressure pulses. During such events wave growth is expected to be maximum close to the magnetopause. In previous studies, distribution of EMIC waves was analyzed according to their distance from the Earth, which is inadequate for studying the magnetopause region. We map a data set of EMIC waves observed by Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft according to their distance from case‐by‐case modeled magnetopause. EMIC occurrence rate is found to be maximum within two Earth radii from the magnetopause and then it linearly decreases with an increasing distance, especially close to the local noon. Asymmetries between the morning and evening magnetic sectors are explained by asymmetries in the upstream conditions and by the presence of another EMIC population of a different origin.

中文翻译：

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EMIC波在磁层中的出现，取决于它们到磁层顶的距离

在外磁层中观察到的电磁离子回旋加速器（EMIC）辐射的波增长主要受太阳风动压力脉冲引起的压缩事件控制。在这样的事件中，预计波的增长将最大程度接近磁层顶。在以前的研究中，根据EMIC波与地球之间的距离来分析EMIC波的分布，这不足以研究磁层顶区。我们根据事件与时间的历史记录以及在亚暴期间（THEMIS）航天器与宏观相互作用的观测，绘制了一个EMIC波的数据集，这是根据它们与逐例建模的磁更年期之间的距离得出的。发现EMIC的发生率在距磁绝顶的两个地球半径之内最大，然后随着距离的增加而线性减小，尤其是在接近当地正午时。