Detection and Description of the Different Ionospheric Disturbances that Appeared during the Solar Eclipse of 21 August 2017

This work will provide a detailed characterization of the travelling ionospheric disturbances (TIDs) created by the solar eclipse of 21 August 2017, the shadow of which crossed the United States from the Pacific to the Atlantic ocean. The analysis is done by means of the Atomic Decomposition Detector of Traveling Ionospheric Disturbances (ADDTID) algorithm. This method automatically detects and characterizes multiple TIDs from the global navigation satellite system (GNSS) observation. The set of disturbances generated by the eclipse has a richer and more varied behavior than that associated with the shock wave directly produced by cooling effects of the moon shadow. This can be modeled in part as if the umbra and penumbra of the eclipse were moving cylinders that intersects with variable elevation angle a curved surface. This projection gives rise to regions of equal penumbra with shapes similar to ellipses, with different centers and foci. The result of this is reflected in the time evolution of the TID wavelengths produced by the eclipse, which depend on the vertical angle of the sun with the surface of the earth, and also a double bow wave phenomenon, where the bow waves are generated in advance to the umbra. We show that the delay in the appearance of the disturbances with the transit of the eclipse are compatible with the physical explanations, linked to the different origins of the disturbances and the wavelengths. Finally, we detected a consistent pattern, in location and time of disturbances in advance to the penumbra as a set of medium scale TIDs, which could be hypothesized as soliton waves of the bow wave. In all cases, the detected disturbances were checked visually on the detrended vertical total electron content (TEC) maps.

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Ionospheric response to total solar eclipse of 22 July 2009 in different Indian regions

Annales Geophysicae ◽

10.5194/angeo-31-1549-2013 ◽

2013 ◽

Vol 31 (9) ◽

pp. 1549-1558 ◽

Cited By ~ 17

Author(s):

S. Kumar ◽

A. K. Singh ◽

R. P. Singh

Keyword(s):

Total Electron Content ◽

Solar Eclipse ◽

Total Solar Eclipse ◽

Lower Atmosphere ◽

Electron Content ◽

Vertical Total Electron Content ◽

Total Electron ◽

Ionospheric Response ◽

Total Electron Content Data ◽

Photoionization Process

Abstract. The variability of ionospheric response to the total solar eclipse of 22 July 2009 has been studied analyzing the GPS data recorded at the four Indian low-latitude stations Varanasi (100% obscuration), Kanpur (95% obscuration), Hyderabad (84% obscuration) and Bangalore (72% obscuration). The retrieved ionospheric vertical total electron content (VTEC) shows a significant reduction (reflected by all PRNs (satellites) at all stations) with a maximum of 48% at Varanasi (PRN 14), which decreases to 30% at Bangalore (PRN 14). Data from PRN 31 show a maximum of 54% at Kanpur and 26% at Hyderabad. The maximum decrement in VTEC occurs some time (2–15 min) after the maximum obscuration. The reduction in VTEC compared to the quiet mean VTEC depends on latitude as well as longitude, which also depends on the location of the satellite with respect to the solar eclipse path. The amount of reduction in VTEC decreases as the present obscuration decreases, which is directly related to the electron production by the photoionization process. The analysis of electron density height profile derived from the COSMIC (Constellation Observing System for Meteorology, Ionosphere & Climate) satellite over the Indian region shows significant reduction from 100 km altitude up to 800 km altitude with a maximum of 48% at 360 km altitude. The oscillatory nature in total electron content data at all stations is observed with different wave periods lying between 40 and 120 min, which are attributed to gravity wave effects generated in the lower atmosphere during the total solar eclipse.

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Analysis of a new regional ionospheric assimilated H2PT model for Europe

10.5194/egusphere-egu2020-1524 ◽

2020 ◽

Author(s):

Paulina Woźniak ◽

Anna Świątek ◽

Mariusz Pożoga ◽

Łukasz Tomasik

Keyword(s):

Spatial Resolution ◽

Negative Impact ◽

Satellite System ◽

Electron Content ◽

Maximum Height ◽

Vertical Total Electron Content ◽

Dual Frequency ◽

International Gnss Service ◽

Statistical Parameters ◽

Total Electron

The signal emitted by the GNSS (Global Navigation Satellite System) satellite, on the way to the receiver located on the Earth&#8217;s surface, encounters a heterogeneous layer of ionized gas and free electrons, in which the radio wave is dispersed. As the ionosphere is the source of the highest-value errors among the different factors that affect GNSS positioning accuracy, it is necessary to minimize its negative impact. Various methods are used to compensate for the ionospheric delay, one of which is the usage of models. The intensity of the processes occurring in the ionosphere is closely related to the Sun activity. As a consequence, with respect to a given location on the Earth's surface, the activity of the ionosphere changes throughout the year and day. Therefore, a model dedicated to a specific region is especially important in case of high-precision GNSS applications. The assimilated H2PT model was based on the dual-frequency observations from GNSS stations belonging to EPN (EUREF Permanent Network), as well as on ionosondes participating in the DIAS (European Digital Upper Atmosphere Server) project. The H2PT model covers the Europe area, data with a 15-minutes interval were placed in similar to IONEX (IONosphere Map EXchenge) files in two versions of spatial resolution: 1- and 5-degree. Data provided by the H2PT model are the VTEC (Vertical Total Electron Content) values and the hmF2 (maximum height of the F2 layer) parameters. The subject of this research is the comparison of the H2PT model with NeQuick-G model and IONEX data published by IGS (International GNSS Service) in the context of TEC values as well as determining differences between regional hmF2 data and its commonly used fixed value for the entire globe, amounting to 450 km. In order to perform the analysis, appropriate visualizations were made and statistical parameters determined. Additionally, data from selected periods of positive and negative disturbances were analysed in details based on the developed time series. The relatively high temporal and spatial resolution is undoubtedly an advantage of the H2PT model, because unlike global models, the regional one allows conscientious analysis of the ionosphere characteristics for the area of Europe. Importantly, solutions regarding hmF2 show significant deviations from the fixed value approximated for the whole Earth. Taking into account the parameter appropriate for a given location and time during GNSS data processing may improve the obtained positioning quality.&#160;

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Three-dimensional Tomography of Coseismic Ionospheric Disturbances from the 2016 West Sumatera Earthquake

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/936/1/012022 ◽

2021 ◽

Vol 936 (1) ◽

pp. 012022

Author(s):

R W Rahayu ◽

M N Cahyadi ◽

B Muslim ◽

I M Anjasmara ◽

E Y Handoko ◽

...

Keyword(s):

Three Dimensional ◽

Temporal Analysis ◽

Satellite System ◽

Electron Content ◽

Ionospheric Disturbances ◽

Total Electron ◽

3D Tomography ◽

West Sumatra ◽

3D Information ◽

Global Navigation Satellite

Abstract Global Navigation Satellite System (GNSS) is a navigation system that uses satellite signals to determine its position, which consists of several satellites arranged in a constellation system. GNSS transmits signals to receivers on Earth. The GNSS receiver determines the user’s position, speed, and time by processing the signals transmitted by the satellites. The initial purpose of launching the GNSS was for navigation purposes, but along with its development, GNSS can be used for the purposes of observing deformation of the earth’s crust and in studying the atmosphere. The delayed wave data when passing through the ionosphere can be used to obtain Total Electron Content (TEC) values which then used to study ionospheric disturbances. Ionospheric disturbances are caused by various phenomena, the most common one is the ionospheric disturbances caused by the induction of acoustic and gravitational waves excited by co seismic crustal motions from large earthquakes. Ionospheric disturbances that happened before an earthquake are called Pre-seismic Ionospheric Disturbances and those that occur after an earthquake are called Co-seismic Ionospheric Disturbances (CID). Most studies of ionospheric disturbances still provide information on the timing and value of TEC anomalies in 2D form. Therefore, in this study, a 3D ionosphere profile modelling using computed 3D tomography will be carried out. The 3D information provided is in the form of time, ionosphere altitude and TEC anomaly value by utilizing GNSS data. The TEC anomaly value is obtained from the calculation of linear combination of the ionosphere. This study aims to obtain a spatial and temporal analysis of the CID caused by the West Sumatra Earthquake on March 2, 2016.

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A multi-instrumental and modelling analysis of the ionospheric responses to the solar eclipse of December 14, 2020, over the Brazilian region

10.5194/angeo-2021-61 ◽

2021 ◽

Author(s):

Laysa Cristina Araujo Resende ◽

Yajun Zhu ◽

Clezio Marcos Denardini ◽

Sony Su Chen ◽

Ronan Arraes Jardim Chagas ◽

...

Keyword(s):

Solar Eclipse ◽

Satellite System ◽

Electron Content ◽

Electronic Density ◽

Total Electron ◽

Density Reduction ◽

Modelling Analysis ◽

E Region ◽

South Of Brazil ◽

Global Navigation Satellite

Abstract. This work presents an analysis of the ionospheric responses to the solar eclipse that occurred on December 14, 2020, over the Brazilian sector. This event partially covers the south of Brazil, providing an excellent opportunity to study the modifications in the peculiarities that occur in this sector, as the Equatorial Ionization Anomaly (EIA). Therefore, we used the Digisonde data available in this period for two sites, Campo Grande (CG, 20.47° S, 54.60° W, dip ∼23° S) and Cachoeira Paulista (CXP, 22.70° S, 45.01° W, dip ∼35° S), assessing the E, and F regions, and Es layer behaviors. Additionally, a numerical model (MIRE, Portuguese acronym for E Region Ionospheric Model) is used to analyze the E layer dynamics modification around these times. The results show the F1 region disappearance and an apparent electronic density reduction in the E region during the solar eclipse. We also analyzed the total electron content (TEC) maps from the Global Navigation Satellite System (GNSS) that indicate a weakness in the EIA. On the other hand, we observe the rise of the Es layer electron density, which is related to the gravity waves strengthened during solar eclipse events. Finally, our results lead to a better understanding of the restructuring mechanisms in the ionosphere at low latitudes during the solar eclipse events, even though they only partially reached the studied regions.

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MGR-DCB: A Precise Model for Multi-Constellation GNSS Receiver Differential Code Bias

Journal of Navigation ◽

10.1017/s0373463315000922 ◽

2015 ◽

Vol 69 (4) ◽

pp. 698-708 ◽

Cited By ~ 6

Author(s):

Mohamed Abdelazeem ◽

Rahmi N. Çelik ◽

Ahmed El-Rabbany

Keyword(s):

Total Electron Content ◽

Satellite System ◽

Mean Difference ◽

Electron Content ◽

Vertical Total Electron Content ◽

International Gnss Service ◽

Total Electron ◽

Differential Code Bias ◽

Gnss Receiver ◽

Code Bias

In this study, we develop a Multi-constellation Global Navigation Satellite System (GNSS) Receiver Differential Code Bias (MGR-DCB) model. The model estimates the receiver DCBs for the Global Positioning System (GPS), BeiDou and Galileo signals from the ionosphere-corrected geometry-free linear combinations of the code observations. In order to account for the ionospheric delay, a Regional Ionospheric Model (RIM) over Europe is developed. GPS observations from 60 International GNSS Servoce (IGS) and EUREF reference stations are processed in the Bernese-5·2 Precise Point Positioning (PPP) module to estimate the Vertical Total Electron Content (VTEC). The RIM has spatial and temporal resolutions of 1° × 1° and 15 minutes, respectively. The receiver DCBs for three stations from the International GNSS Service Multi-GNSS Experiment (IGS-MGEX) are estimated for three different days. The estimated DCBs are compared with the MGEX published values. The results show agreement with the MGEX values with mean difference and Root Mean Square Error (RMSE) values less than 1 ns. In addition, the combined GPS, BeiDou and Galileo VTEC values are evaluated and compared with the IGS Global Ionospheric Maps (IGS-GIM) counterparts. The results show agreement with the GIM values with mean difference and RMSE values less than 1 Total Electron Content Unit (TECU).

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ADDTID: An Alternative Tool for Studying Earthquake/Tsunami Signatures in the Ionosphere. Case of the 2011 Tohoku Earthquake

Remote Sensing ◽

10.3390/rs11161894 ◽

2019 ◽

Vol 11 (16) ◽

pp. 1894 ◽

Cited By ~ 1

Author(s):

Heng Yang ◽

Enrique Monte Moreno ◽

Manuel Hernández-Pajares

Keyword(s):

Acoustic Waves ◽

Tohoku Earthquake ◽

Location Estimation ◽

Electron Content ◽

Ionospheric Disturbances ◽

Vertical Total Electron Content ◽

The 2011 Tohoku Earthquake ◽

Total Electron ◽

Acoustic Gravity Waves ◽

Traveling Ionospheric Disturbances

In this work, we characterized the ionospheric disturbances generated during the Japan Tohoku earthquake of 11 March 2011, by means of the Atomic Decomposition Detector of Traveling Ionospheric Disturbances (ADDTID) algorithm. This algorithm automatically detects and characterizes Traveling Ionospheric Disturbances (TIDs) from Global Navigation Satellite System (GNSS) measurements. Applying the high-precision estimates of ADDTID, the propagation parameters would make it easier to distinguish TIDs from different origins, in particular the characteristics conforming the acoustic gravity waves driven by the earthquake/tsunami. This method does not assume that disturbances follow a circular pattern of propagation, and can estimate the location by the propagation pattern of tsunami wavefronts and related TIDs. In this work, we present in a single framework a description of phenomena observed by different researchers. By means of the ADDTID algorithm, we detect: (a) simultaneous TIDs of different characteristics, where the detection was robust against the curvature of the wave fronts of the perturbations and the accuracy of the estimated parameters. The results were double-checked by visual inspection from detrended Vertical Total Electron Content (VTEC) maps and keogram plots, and the parameters of the slow-speed TIDs were consistent with the tsunami waveform measurements; (b) different wavefronts between the west and east TIDs around the epicenter, consistent in time and space with the post-earthquake tsunami; (c) complete evolution of the circular TIDs driven by the tsunami during the GNSS observable area; (d) fast and short circular TIDs related to the acoustic waves of earthquake; (e) the pre-seismic activity consisting of a set of fast westward TIDs, and the comparison with neighboring days; (f) the location estimation of the tsunami wavefront along the coast and the possible use as early warning. Finally, we report disturbances that had not been previously published with a possible application to local and real-time detection of tsunamis.

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Degradation of Kinematic PPP of GNSS Stations in Central Europe Caused by Medium-Scale Traveling Ionospheric Disturbances During the St. Patrick’s Day 2015 Geomagnetic Storm

Remote Sensing ◽

10.3390/rs12213582 ◽

2020 ◽

Vol 12 (21) ◽

pp. 3582

Author(s):

Mateusz Poniatowski ◽

Grzegorz Nykiel

Keyword(s):

Central Europe ◽

Geomagnetic Storm ◽

Activity Index ◽

Satellite System ◽

Electron Content ◽

Ionospheric Disturbances ◽

Total Electron ◽

Traveling Ionospheric Disturbances ◽

Cycle Slips ◽

The Impact

In solar cycle 24, the strongest geomagnetic storm took place on 17 March 2015, when the geomagnetic activity index was as high as −223 nT. To verify the impact that the storm had on the Global Navigation Satellite System (GNSS)’s positioning accuracy and precision, we used 30-s observations from 15 reference stations located in Central Europe. For each of them, we applied kinematic precise point positioning (PPP) using gLAB software for the day of the storm and, for comparison, for a selected quiet day (13 March 2015). Based on the conducted analyses, we found out that the position root mean square (RMS) values on the day of the geomagnetic storm were significantly high and amounted to several dozen centimeters. The average RMS for the altitude coordinates was 0.58 m between 12:00 and 24:00 (GPS time), and 0.37 and 0.26 m for directions North and East, respectively. The compromised accuracy level was caused by a sudden decrease in the number of satellites used for calculations. This was due to a high number of cycle slips (CSs) detected during this period. The occurrence of these effects was strictly correlated with the appearance of traveling ionospheric disturbances (TIDs). This was proven by analyzing changes in the total electron content (TEC) estimated for each station–satellite pair.

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Ionospheric perturbation during the South American total solar eclipse on 14th December 2020 revealed with the Chilean GPS eyeball

Scientific Reports ◽

10.1038/s41598-021-98727-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mahesh N. Shrivastava ◽

Ajeet Kumar Maurya ◽

Kondapalli Niranjan Kumar

Keyword(s):

Plasma Density ◽

Solar Eclipse ◽

Density Perturbation ◽

Total Solar Eclipse ◽

Electron Content ◽

Vertical Total Electron Content ◽

South American ◽

The South ◽

Total Electron ◽

Atmospheric Gravity

AbstractThe influence of the South American total solar eclipse of 14th December 2020 on the ionosphere is studied by using the continuous Chilean Global Positioning System (GPS) sites across the totality path. The totality path with eclipse magnitude 1.012 passed through the Villarrica (Lon. 72.2308°W and Lat. 39.2820°S) in south Chile during 14:41:02.0 UTC to 17:30:58.1 UTC and maximum occurred ~ 16:03:49.5 UTC around the local noon. The vertical total electron content (VTEC) derived by GPS sites across the totality path for two PRN’s 29 and 31 show almost 20–40% of reduction with reference to ambient values. The percentage reduction was maximum close to totality site and decreases smoothly on both sides of totality sites. Interestingly, the atmospheric gravity waves (AGWs) with a period ~ 30–60 min obtained using wavelet analysis of VTEC timeseries show the presence of strong AGWs at the GPS sites located north of the totality line. But the AGWs do not show any significant effect on the VTEC values to these sites. Our analysis suggests, possibly an interplay between variability in the background plasma density and eclipse-generated AGWs induced plasma density perturbation could explain the observations.

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A Comprehensive Analysis of Ionospheric Anomalies before the Mw7·1 Van Earthquake on 23 October 2011

Journal of Navigation ◽

10.1017/s0373463318000826 ◽

2018 ◽

Vol 72 (3) ◽

pp. 702-720 ◽

Cited By ~ 4

Author(s):

Erman Şentürk ◽

Hamdullah Livaoğlu ◽

Murat Selim Çepni

Keyword(s):

Total Electron Content ◽

Activity Index ◽

Satellite System ◽

Electron Content ◽

Vertical Total Electron Content ◽

International Gnss Service ◽

Van Earthquake ◽

Total Electron ◽

Interdisciplinary Approaches ◽

The Van Earthquake

In this study, possible ionospheric precursors of the Mw7·1 Van earthquake are investigated with temporal, spatial and spectral analyses. For this purpose, Global Navigation Satellite System (GNSS) data of 11 International GNSS Service (IGS) stations and 17 Turkish National Permanent Real-Time Kinematic (RTK) Network (TNPGN-Active) stations were utilised. In addition, Global Ionosphere Map (GIM) data produced by the Center for Orbit Determination in Europe (CODE) was used to obtain GIM-vertical Total Electron Content (vTEC) values for the epicentre. The results of the temporal and spectral analysis indicate an increase (2–8 Total Electron Content Units (TECU)) before the Van earthquake occurred on 9 October, 15–16 October and 21–23 October within 15 days, 8–9 days and 1–3 days prior to the earthquake. The Cross-Wavelet Transform (CWT) method was used to examine the presence of correlation between noticeable variations and space-weather. It is deduced from the CWT analysis that the anomalies should originate from either solar effects or the Van earthquake due to coupling between the F10·7 solar activity index and TEC variations on the anomaly days. The results demonstrate that interdisciplinary approaches and various methods including frequency domain could be used to determine the presence of an earthquake-related anomaly in the ionosphere accurately.

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Ionospheric Response over Nepal during the 26 December 2019 Solar Eclipse

Journal of Nepal Physical Society ◽

10.3126/jnphyssoc.v7i1.36970 ◽

2021 ◽

Vol 7 (1) ◽

pp. 25-30

Author(s):

A. Silwal ◽

S. P. Gautam ◽

N. P. Chapagain ◽

M. Karki ◽

P. Poudel ◽

...

Keyword(s):

Solar Eclipse ◽

Satellite System ◽

Electron Content ◽

Total Electron ◽

North West ◽

North East ◽

Apparent Variation ◽

Gnss Measurements ◽

Global Navigation Satellite ◽

Annular Solar Eclipse

On 26th December 2019, during morning hours, an annular solar eclipse having a magnitude of 0.96 with a 118 km wide antumbra occurred and lasted for 3 minutes and 40 seconds at the point of maximum eclipse. The partial eclipse was visible in most of Asia, parts of North/East Africa, and North/West Australia. In the context of Nepal, only the partial eclipse was visible from ~ 8:34 LT (02:51 UT) and ended at ~ 11:40 LT (05:55 UT). It was 2 hours 47 mins and 54 secs long with the maximum visible eclipse time at ~ 10:01 LT (04:16 UT). Our study is based on Global Navigation Satellite System (GNSS) measurements from a widely distributed Global Positioning System (GPS) network over different places of Nepal on the day of the eclipse, a day before, and a day after the eclipse. We investigated the ionospheric behavior through the changes in Total Electron Content (TEC) during the partial eclipse by using the data archived at the five different GPS stations of Nepal. The result reveals that there is significant depletion of TEC, in some cases greater than 20% compared to other normal days. Observing the values of TEC before, during, and after the event, our study showed an apparent variation during the time of the eclipse, which agrees with previous studies on ionospheric responses to the eclipse as well as theoretical assumptions.

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