Abstract

This paper discusses the spectral and temporal features of the 7-h daytime VLF noise emission burst in the frequency band of 1‒10 kHz observed on the Earth’s surface during the late recovery phase of a moderate magnetic storm (Kр = 5 and Dst ~ –80 nT) under nearly quiet space weather. These VLF emissions were recorded simultaneously at two auroral stations located at a geomagnetic latitude of ~64° MLAT and at a longitude distance of ~400 km from each other: Finnish Kannuslehto Station (KAN) and Russian Lovozero Observatory (LOZ). The dynamic VLF wave spectrum is considered at different time scales. During the development of the discussed daytime VLF burst, the noise emissions at below 3.5 kHz gradually turn into periodic (QP) emissions with a quasi-repetition of ~3 s. Having compared the directions of short isolated high-frequency (above 5 kHz) VLF signals (so-called “birds”) arriving at KAN and LOZ, we draw conclusions on the possible location and spatial dynamics of the exit area of emission from the ionosphere.

中文翻译：

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电磁风暴恢复阶段的白天VLF排放：2015年1月5日事件

摘要

本文讨论期间中等磁性风暴（后期恢复阶段在地球表面上观察到1-10千赫的频带突发7-H白天VLF噪声发射的频谱和时间特性Kр = 5和Dst的〜 - 80 nT）在几乎安静的太空天气下。在两个地磁纬度为MLAT且距彼此相距约400 km的极光站同时记录了这些VLF排放：芬兰Kannuslehto站（KAN）和俄罗斯Lovozero天文台（LOZ）。动态VLF频谱在不同的时间尺度上被考虑。在讨论的白天VLF突发的发展过程中，低于3.5 kHz的噪声发射逐渐变成周期性的（QP）的发射，重复时间约为3 s。比较了到达KAN和LOZ的短隔离高频（5 kHz以上）VLF信号（所谓的“鸟”）的方向后，我们得出了关于电离层发射出射区域的可能位置和空间动力学的结论。 。