Singular Spectrum Analysis of the Total Electron Content Changes Prior to M ≥ 6.0 Earthquakes in the Chinese Mainland During 1998–2013
Singular Spectrum Analysis of the Total Electron Content Changes Prior to M ≥ 6.0 Earthquakes in the Chinese Mainland During 1998–2013
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DOI：
10.3389/feart.2021.677163
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发表时间：
2021-05
期刊：
影响因子：
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通讯作者：
Hongyan Chen;Miao Miao-Miao;Ying Chang;Qiao Wang;X. Shen;K. Hattori;Peng Han
中科院分区：
文献类型：
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作者：
Hongyan Chen;Miao Miao-Miao;Ying Chang;Qiao Wang;X. Shen;K. Hattori;Peng Han
早期的研究表明，在大地震之前，地震-电离层扰动的证据。由于电离层动态的复杂性，电离层前兆变化的识别具有很大的挑战性。本文分析了1998-2013年中国大陆6.0级以上地震前全球电离层总电子含量（TEC）的变化，并对TEC的变化进行了研究，以寻找可能的地震-电离层前兆。利用奇异谱分析方法提取了以太阳活动为主的日、半日分量的趋势和周期变化。残差ΔTEC主要由地震和地磁活动引起的误差和可能的扰动组成，并采用均方根误差检测异常变化。当太阳或地磁活动强烈时，F10.7和Dst指数也被用作排除异常的标准。我们的结果与以前的研究结果一致。证实了0600 ~ 1000t时，地震前1 ~ 5天在定点（35°N, 90°E）负异常占优势，在震中附近异常更为明显。奇异谱分析方法有助于建立更可靠的TEC变化背景，从而提高对电离层前兆变化的识别。
Early studies have shown evidence of the seismo-ionospheric perturbations prior to large earthquakes. Due to dynamic complexity in the ionosphere, the identification of precursory ionospheric changes is quite challenging. In this study, we analyze the total electron content (TEC) in the global ionosphere map and investigate the TEC changes prior to M ≥ 6.0 earthquakes in the Chinese Mainland during 1998–2013 to identify possible seismo-ionospheric precursors. Singular spectrum analysis is applied to extract the trend and periodic variations including diurnal and semi-diurnal components, which are dominated by solar activities. The residual ΔTEC which is mainly composed of errors and possible perturbations induced by earthquakes and geomagnetic activities is further investigated, and the root-mean-square error is employed to detect anomalous changes. The F10.7 and Dst index is also used as criterion to rule out the anomalies when intense solar or geomagnetic activities occur. Our results are consistent with those of previous studies. It is confirmed that the negative anomalies are dominant 1–5 days before the earthquakes at the fixed point (35°N, 90°E) during 0600–1000 LT. The anomalies are more obvious near the epicenter area. The singular spectrum analysis method help to establish a more reliable variation background of TEC and thus may improve the identification of precursory ionospheric changes.