scholarly journals Ionospheric turbulence from TEC variations and VLF/LF transmitter signal observations before and during the destructive seismic activity of August and October 2016 in Central Italy

2020 ◽  
Vol 63 (5) ◽  
Author(s):  
Michael Contadakis ◽  
Demetrios Arabelos ◽  
George Vergos ◽  
Christos Skeberis ◽  
Tomas Xenos ◽  
...  
Keyword(s):  
Seismic Activity ◽  
Visual Analysis ◽  
Central Italy ◽  
Electron Content ◽  
Ionospheric Turbulence ◽  
Total Electron ◽  
Discrete Fourier Analysis ◽  
Hilbert Huang Transform ◽  
Global Positioning ◽  
The Moment

In this paper we investigate the ionospheric turbulence from observations of TEC variations as well as from VLF/LF transmitter signal observations before and during the disastrous seismic activity of August and October 2016 in Central Italy. The Total Electron Content (TEC) data of 8 Global Positioning System (GPS) stations of the EUREF network, which are being provided by IONOLAB (Turkey), were analysed using Discrete Fourier Analysis in order to investigate the TEC variations. The data acquired for VLF/LF signal observations are from the receiver of Thessaloniki (40.59N, 22,78E), Greece, which monitor the VLF/LF transmitters of the International Network for Frontier Research on Earthquake Precursors (INFREP). A method of normalization according to the distance between the receiver and the transmitter is applied on the above data and then they are processed by the Hilbert Huang Transform (HHT) to produce the corresponding spectra for visual analysis. The results of both methods indicate that the High- Frequency limit fo, of the ionospheric turbulence content, increases as the site and the moment of the earthquake occurrence is approaching, pointing to the earthquake locus.

Lower Ionospheric turbulence variations during the intense seismic activity of the last half of 2019 in the broader Balkan region.

2020 ◽  
Author(s):  
Michael E. Contadakis ◽  
Demetrios Arabelos ◽  
George Vergos ◽  
Emmanuel M. Scordilis
Keyword(s):  
Global Positioning System ◽  
Seismic Activity ◽  
Main Shock ◽  
Electron Content ◽  
Marmara Sea ◽  
Ionospheric Turbulence ◽  
Total Electron ◽  
Discrete Fourier Analysis ◽  
Global Positioning ◽  
Balkan Region

<p>In this paper, we investigate the ionospheric turbulence from TEC observations, before and during the intense seismic activity of September 2019 at Albania (main shock at l=19.445<sup>o</sup>E, j=41.372<sup>o</sup> N, M<sub>w</sub>=5.6)  and at Marmara sea (main shock at l=28.19 <sup>o</sup>E, j=40.872<sup>o</sup>N, M<sub>w</sub>=5.7), as well as of November 2019 at Albania (main shock at l=19.470<sup>o</sup>E, j=41.381<sup>o</sup>N, M<sub>w</sub>=6.4), and at Bosnia-Herzegovina (main shock at l=17.961<sup>o</sup>E, j=43.196<sup>o</sup>N, M<sub>w</sub>=5.4).</p><p>The Total Electron Content (TEC) data of 6 Global Positioning System (GPS) stations of the EUREF network, which are being provided by IONOLAB (Turkey), were analysed using Discrete Fourier Analysis in order to investigate the TEC variations. The results of this investigation indicate that the High- Frequency limit f<sub>o</sub>, of the ionospheric turbulence content, increases by aproaching the site and  the time of the earthquake occurrence, pointing to the earthquake location (epicenter). We conclude that the LAIC mechanism, through acoustic or gravity wave, could explain this phenomenology. In addition the proximity of the tectonic active areas to the GPS stations offer us an opportunity to discriminate the origin of the disturbances</p>

Lower Ionospheric turbulence variations during the tectonic activity of the last quarter of 2019 in the Hellenic Arc (Greece)

2020 ◽  
Author(s):  
Dimitrios N. Arabelos ◽  
Michael E. Contadakis ◽  
George Vergos ◽  
Emmanuel M. Scordilis
Keyword(s):  
Global Positioning System ◽  
High Frequency ◽  
Main Shock ◽  
Tectonic Activity ◽  
Electron Content ◽  
Ionospheric Turbulence ◽  
Total Electron ◽  
Discrete Fourier Analysis ◽  
Hellenic Arc ◽  
Global Positioning

<p>In this paper we investigate the ionospheric turbulence from TEC observations before and during the tectonic activity of the last quarter of 2019 in the Hellenic Arc, Greece (main shock at l=23.26<sup>o</sup>E, j=35.69<sup>o</sup>N, M<sub>w</sub>=6.1). The Total Electron Content (TEC) data of 6 Global Positioning System (GPS) stations of the EUREF network, which are being provided by IONOLAB (Turkey), were analysed using Discrete Fourier Analysis in order to investigate the TEC variations. The results of this investigation indicate that the High- Frequency limit f<sub>o</sub>, of the ionospheric turbulence content, increases by aproaching the site and the time of the earthquake occurrence, pointing to the earthquake location (epicenter). We conclude that the LAIC mechanism through acoustic or gravity wave could explain this phenomenology.</p>

scholarly journals On a reported effect in ionospheric TEC around the time of the 6 April 2009 L'Aquila earthquake

2017 ◽  
Vol 17 (9) ◽  
pp. 1461-1468 ◽  
Author(s):  
Fabrizio Masci ◽  
Jeremy N. Thomas ◽  
James A. Secan
Keyword(s):  
Global Positioning System ◽  
Main Shock ◽  
Central Italy ◽  
Electron Content ◽  
Total Electron ◽  
Total Electron Content Data ◽  
Independent Analysis ◽  
2009 L’Aquila Earthquake ◽  
Global Positioning ◽  
The Hours

Abstract. In a report published in Advances in Space Research, Nenovski et al. (2015) analyse ionospheric TEC (total electron content) data from GPS measurements around the time of the 6 April 2009 Mw 6. 1 L'Aquila (Italy) earthquake. According to the authors, TEC difference (DTEC) calculated from two GPS (Global Positioning System) receivers in central Italy shows a hump-like shape (an increase followed by a decrease) during the hours just before and shortly after the main shock. They maintain that the hump-like shape is anomalous and may be related to the earthquake. We show that the DTEC increase in the hours before the shock, as well as its subsequent slow decrease, does not have any characteristic that might support a possible relationship with the earthquake. We have also conducted our own independent analysis using the same GPS data analysed by Nenovski et al. (2015). We have found a diurnal variation in DTEC time series that shows hump-like shapes like that reported by Nenovski et al. (2015) throughout the investigated period. This demonstrates that the hump-like shape in DTEC close to the time of the 6 April earthquake is not anomalous and cannot be considered a possible earthquake-related effect.

scholarly journals Comparison of GPS TEC with IRI models of 2007, 2012, AND 1 2016 over Sukkur, Pakistan

2020 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Adil Hussain ◽  
Munawar Shah
Keyword(s):  
Global Positioning System ◽  
Electron Content ◽  
Iri Model ◽  
Low Latitude ◽  
Total Electron ◽  
Gps Tec ◽  
Global Positioning ◽  
Radio Signals ◽  
Ionospheric Scintillations ◽  
Latitude Region

The international reference ionosphere (IRI) models have been widely used for correcting the ionospheric scintillations at different altitude levels. An evaluation on the performance of VTEC correction from IRI models (version 2007, 2012 and 2016) over Sukkur, Pakistan (27.71º N, 68.85º E) is presented in this work. Total Electron Content (TEC) from IRI models and GPS in 2019 over Sukkur region are compared. The main aim of this comparative analysis is to improve the VTEC in low latitude Sukkur, Pakistan. Moreover, this study will also help us to identify the credible IRI model for the correction of Global Positioning System (GPS) signal in low latitude region in future. The development of more accurate TEC finds useful applications in enhancing the extent to which ionospheric influences on radio signals are corrected. VTEC from GPS and IRI models are collected between May 1, 2019 and May 3, 2019. Additionally, Dst and Kp data are also compared in this work to estimate the geomagnetic storm variations. This study shows a good correlation of 0.83 between VTEC of GPS and IRI 2016. Furthermore, a correlation of 0.82 and 0.78 is also recorded for IRI 2012 and IRI 2007 respectively, with VTEC of GPS. The IRI TEC predictions and GPS-TEC measurements for the studied days reveal the potential of IRI model as a good candidate over Pakistan.

Variability of GPS-derived Ionospheric TEC over Nigeria during a year of low solar activity

2020 ◽  
Author(s):  
G.A. Akinyemi ◽  
L.B. Kolawole ◽  
O.F. Dairo ◽  
Alexander A. Willoughby ◽  
R.B. Abdulrahim ◽  
...  
Keyword(s):  
Global Positioning System ◽  
Electron Content ◽  
Gps Receiver ◽  
Total Electron ◽  
Ionospheric Total Electron Content ◽  
Global Positioning ◽  
Variability Index ◽  
Gnss Network ◽  
Tec Variability ◽  
Anomaly Region

An investigation on the diurnal and seasonal variability of ionospheric Total Electron Content (TEC) over Nigeria is carried out in this study using Global Positioning System (GPS) observable. Nigeria coordinates fall within the trough of equatorial ionization anomaly region of African sector. The TEC data used were obtained from the ground-based GPS receiver stations of the Nigerian GNSS network of stations (NIGNET). The stations with their respective geomagnetic latitudes are Abuja (−1.64º), Yola (−1.32º), Zaria (−0.13º) and Kebbi (0.72º). The results of the diurnal analysis of the relative variability index (VD) revealed higher nighttime values than daytime values. The diurnal variation of VD also showed two conspicuous peaks: the post-midnight and the post-sunset. The diurnal-seasonal variation does not reveal any consistent pattern (no particular season leads the others throughout). On the average, considering all the seasons together maximum TEC variability occurred in Zaria (62%) and least in Yola (54%). Seasonally, maximum VD was recorded during March equinox and the least was recorded during December equinox.

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