scholarly journals Singular Spectrum Analysis of the Total Electron Content Changes Prior to M ≥ 6.0 Earthquakes in the Chinese Mainland During 1998–2013

2021 ◽  
Vol 9 ◽  
Author(s):  
Hongyan Chen ◽  
Miao Miao ◽  
Ying Chang ◽  
Qiao Wang ◽  
Xuhui Shen ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Spectrum Analysis ◽  
Singular Spectrum Analysis ◽  
Chinese Mainland ◽  
Electron Content ◽  
Dynamic Complexity ◽  
Total Electron ◽  
Singular Spectrum ◽  
The Chinese Mainland ◽  
Geomagnetic Activities

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.

Total electron content prediction using singular spectrum analysis and autoregressive moving average approach

2022 ◽  
Vol 367 (1) ◽  
Author(s):  
J. R. K. Kumar Dabbakuti ◽  
Mallika Yarrakula ◽  
Sampad Kumar Panda ◽  
Punyawi Jamjareegulgarn ◽  
Mohd Anul Haq
Keyword(s):  
Total Electron Content ◽  
Spectrum Analysis ◽  
Moving Average ◽  
Singular Spectrum Analysis ◽  
Autoregressive Moving Average ◽  
Electron Content ◽  
Total Electron ◽  
Singular Spectrum

scholarly journals Case study on total electron content enhancements at low latitudes during low geomagnetic activities before the storms

2008 ◽  
Vol 26 (4) ◽  
pp. 893-903 ◽  
Author(s):  
◽  
◽  
◽  
Keyword(s):  
Total Electron Content ◽  
Geomagnetic Activity ◽  
Electron Content ◽  
Low Latitude ◽  
Total Electron ◽  
Defense Meteorological Satellite Program ◽  
Low Latitudes ◽  
Global Ionospheric Maps ◽  
Geomagnetic Activities

Abstract. Sometimes the ionospheric total electron content (TEC) is significantly enhanced during low geomagnetic activities before storms. In this article, we investigate the characteristics of those interesting TEC enhancements using regional and global TEC data. We analyzed the low-latitude TEC enhancement events that occurred around longitude 120° E on 10 February 2004, 21 January 2004, and 4 March 2001, respectively. The TEC data are derived from regional Global Positioning System (GPS) observations in the Asia/Australia sector as well as global ionospheric maps (GIMs) produced by Jet Propulsion Laboratory (JPL). Strong enhancements under low geomagnetic activity before the storms are simultaneously presented at low latitudes in the Asia/Australia sector in regional TEC and JPL GIMs. These TEC enhancements are shown to be regional events with longitudinal and latitudinal extent. The regions of TEC enhancements during these events are confined at narrow longitude ranges around longitude 120° E. The latitudinal belts of maxima of enhancements locate around the northern and southern equatorial ionization anomaly (EIA) crests, which are consistent with those low-latitude events presented by Liu et al. (2008). During the 4 March 2001 event, the total plasma density Ni observed by the Defense Meteorological Satellite Program (DMSP) spacecraft F13 at 840 km altitude are of considerably higher values on 4 March than on the previous day in the TEC enhanced regions. Some TEC enhancement events are possibly due to contributions from auroral/magnetospheric origins; while there are also quasi-periodic enhancement events not related to geomagnetic activity and associated probably with planetary wave type oscillations (e.g. the 6 January 1998 event). Further investigation is warrented to identify/separate contributions from possible sources.

scholarly journals Some statistics of Ionospheric total electron content variations at mid-latitude zones of Mongolia

2021 ◽  
pp. 1-8
Author(s):  
Baatarkhuu Dagva ◽  
Amarjargal Sharav ◽  
Lkhagvajav Chultemiin
Keyword(s):  
Total Electron Content ◽  
Satellite System ◽  
Electron Content ◽  
Sudden Increase ◽  
Dual Frequency ◽  
Total Electron ◽  
Rotation Of The Earth ◽  
Global Navigation Satellite ◽  
Continuous Gps ◽  
Geomagnetic Activities

This work is focused on the correlation of ionosphere total electron content (TEC) with solar and geomagnetic activities of the space weather at mid-latitude zone.  In our analysis, we investigate the TEC time series obtained from dual-frequency GNSS (Global Navigation Satellite System) observations at three continuous GPS/GNSS stations HOVD (48.00N, 91.66E), CHOB (48.08N, 114.53E) and DALN (43.56N, 104.42) for 2013. The statistical analyses are performed on 15 minute averaged yearly TEC values, which reveal the semi-annual anomaly and high correlation with the activities of the Sun and the rotation of the Earth. Phase overlapping seasonal variations of TEC and Sunspot, and Solar flux (10.7) indices, and Earth rotations (LOD) and Atmospheric angular moment (AAM) are observed in our data analyses. Sudden ionospheric storm changes in TEC with geomagnetic storm induced by the extreme solar flare and 2013 events were investigated. The result shows that GPS derived TEC behaves as an indicator of these events showing sudden increase in TEC during the event.

scholarly journals Seismic-Lonospheric Perturbations in Lonospheric TEC and Plasma Parameters Associated with the 14 July 2019 Mw7.2 Laiwui Earthquake Detected by the GPS and CSES

2021 ◽  
Author(s):  
Yuanzheng Wen ◽  
Guangxue Wang ◽  
Dan Tao ◽  
Jiayi Zong ◽  
Zhima Zeren ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Langmuir Probe ◽  
Ionospheric Plasma ◽  
Spatial Variations ◽  
Negative Anomaly ◽  
Electron Content ◽  
Plasma Parameters ◽  
Total Electron ◽  
Ionospheric Perturbations ◽  
Geomagnetic Activities

Abstract In this study, with cross-valid analysis of total electron content (TEC) data of the global ionospheric map (GIM) from GPS and plasma parameters data recorded by China Seismo-Electromagnetic Satellite (CSES), signatures of seismic-ionospheric perturbations related to the 14 July 2019 Mw 7.2 Laiwui earthquake were detected. After distinguishing the solar and geomagnetic activities, three positive temporal anomalies were found around the epicenter 1 day, 3 days and 8 days before the earthquake (14 July 2019) along with a negative anomaly 6 days after the earthquake, which also agrees well with the TEC spatial variations in latitude-longitude-time (LLT) maps. To further confirm the anomalies, the ionospheric plasma parameters (electron, O+ and He+ densities) recorded by the Langmuir probe (LAP) and Plasma Analyzer Package (PAP) onboard CSES were analyzed by using the moving mean method (MMM), which also presented remarkable enhancements along the orbits around the epicenter on day 2, day 4 and day 7 before the earthquake. To make the investigations more convincing, the disturbed orbits were compared with their corresponding four nearest revisiting orbits, whose results indeed indicate the existence of plasma parameters anomalies associated with the Laiwui earthquake. All these results illustrated that the GPS and CSES observed unusual ionospheric perturbations are highly associated with the Mw 7.2 Laiwui earthquake, which also strongly indicates the existence of pre-seismic ionospheric anomalies over the earthquake region.

scholarly journals Seismo-ionospheric anomalies in ionospheric TEC and plasma density before the 17 July 2006 <i>M</i>7.7 south of Java earthquake

2017 ◽  
Vol 35 (3) ◽  
pp. 589-598 ◽  
Author(s):  
Dan Tao ◽  
Jinbin Cao ◽  
Roberto Battiston ◽  
Liuyuan Li ◽  
Yuduan Ma ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Plasma Density ◽  
Spatial Variations ◽  
Asymmetric Structure ◽  
Electron Content ◽  
Total Electron ◽  
Significant Evidence ◽  
Demeter Satellite ◽  
Global Ionosphere Map ◽  
Geomagnetic Activities

Abstract. In this paper, we report significant evidence for preseismic ionospheric anomalies in total electron content (TEC) of the global ionosphere map (GIM) and plasma density appearing on day 2 before the 17 July 2006 M7.7 south of Java earthquake. After distinguishing other anomalies related to the geomagnetic activities, we found a temporal precursor around the epicenter on day 2 before the earthquake (15 July 2006), which agrees well with the spatial variations in latitude–longitude–time (LLT) maps. Meanwhile, the sequences of latitude–time–TEC (LTT) plots reveal that the TECs on epicenter side anomalously decrease and lead to an anomalous asymmetric structure with respect to the magnetic equator in the daytime from day 2 before the earthquake. This anomalous asymmetric structure disappears after the earthquake. To further confirm these anomalies, we studied the plasma data from DEMETER satellite in the earthquake preparation zone (2046.4 km in radius) during the period from day 45 before to day 10 after the earthquake, and also found that the densities of both electron and total ion in the daytime significantly increase on day 2 before the earthquake. Very interestingly, O+ density increases significantly and H+ density decreases, while He+ remains relatively stable. These results indicate that there exists a distinct preseismic signal (preseismic ionospheric anomaly) over the epicenter.

scholarly journals Formal estimation of the random component in global maps of total electron content

2016 ◽  
Vol 6 (1) ◽  
pp. 56-60 ◽  
Author(s):  
V. Choliy
Keyword(s):  
Total Electron Content ◽  
Singular Spectrum Analysis ◽  
Satellite System ◽  
Electron Content ◽  
Navigation Satellite ◽  
Random Component ◽  
Optimal Parameters ◽  
Total Electron ◽  
Global Navigation Satellite

Random component of the total electron content (TEC) maps, produced by global navigation satellite system processing centres, was analysed. Helmert transform (HT) and two-dimension singular spectrum analysis (2dSSA) were used. Optimal parameters (in the sense calculation speed versus quality) of the 2dSSA windows were determined along with precision estimations.

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