Comprehensive Morphology of The Spectral Resonance Structure of The Electromagnetic Background Noise In The Range of 0.1-4 Hz At L=5.2
Comprehensive Morphology of The Spectral Resonance Structure of The Electromagnetic Background Noise In The Range of 0.1-4 Hz At L=5.2
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L=5.2时0.1-4 Hz范围内电磁背景噪声谱共振结构的综合形态
DOI：
10.5194/angeo-21-779-2003
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
T. Turunen
中科院分区：
文献类型：
--
作者：
A. Yahnin;N. Semenova;A. Ostapenko;J. Kangas;J. Manninen;T. Turunen
抽象的。利用索丹基拉地球物理观测站(L=5.2)连续观测的地磁场起伏，对0.1HZ-4.0HZ背景电磁噪声中的光谱共振结构进行了全面的形态研究。结果表明，夜间SRS的发生率高于白天。冬季发病率高于夏季。SRS频率和相邻特征频率之差(频率尺度)在夜间增大，白天减小。太阳活动周期的频率尺度和出现率都呈现出从最小到最大逐渐减小的趋势。结果表明，随着地磁活动的增加，受激拉曼散射的发生率降低。SRS被认为是阿尔芬波谐振器的结果，阿尔芬波被认为存在于电离层上层。根据电离层Alfven谐振器(IAR)理论，受激拉曼散射特性主要取决于F层极大值处的电子密度，以及极大值以上密度衰减的高度尺度。计算所需的电离层参数是从电离层模型(IRI-95)以及利用索丹基拉的电离层探空仪进行的测量获得的。我们的结论是，实际上，受激拉曼散射的主要形态性质是在IAR理论的基础上解释的。测得的受激拉曼散射参数可用于改进电离层模型。关键词。电离层(极光电离层；波传播)-无线电科学(电磁噪声和干扰)
Abstract. Continuous observations of fluctuations of the geomagnetic field at Sodankyla Geophysical Observatory (L = 5.2) were used for a comprehensive morphological study of the spectral resonance structure (SRS) seen in the background electromagnetic noise in the frequency range of 0.1–4.0 Hz. It is shown that the occurrence rate of SRS is higher in the nighttime than in the daytime. The occurrence rate is higher in winter than in summer. The SRS frequencies and the difference between neighbouring eigenfrequencies (the frequency scale) increase towards nighttime and decrease towards daytime. Both frequency scale and occurrence rate exhibit a clear tendency to decrease from minimum to maximum of the solar activity cycle. It is found that the occurrence rate of SRS decreases when geomagnetic activity increases. The SRS is believed to be a consequence of a resonator for Alfven waves, which is suggested to exist in the upper ionosphere. According to the theory of the ionospheric Alfven resonator (IAR), characteristics of SRS crucially depend on electron density in the F-layer maximum, as well as on the altitudinal scale of the density decay above the maximum.We compared the SRS morphological properties with predictions of the IAR theory. The ionospheric parameters needed for calculation were obtained from the ionosphere model (IRI-95), as well as from measurements made with the ionosonde in Sodankyla. We conclude that, indeed, the main morphological properties of SRS are explained on the basis of the IAR theory. The measured parameters of SRS can be used for improving the ionospheric models. Key words. Ionosphere (auroral ionosphere; wave propagation) – Radio Science (electromagnetic noise and interference)