scholarly journals Investigation of Ionospheric Response to June 2009 Sarychev Peak Volcano Eruption

2021 ◽  
Vol 13 (4) ◽  
pp. 638
Author(s):  
Nikolay Shestakov ◽  
Alexander Orlyakovskiy ◽  
Natalia Perevalova ◽  
Nikolay Titkov ◽  
Danila Chebrov ◽  
...  
Keyword(s):  
Acoustic Mode ◽  
Global Navigation Satellite Systems ◽  
Electron Content ◽  
Field Zone ◽  
Ionospheric Response ◽  
Satellite Systems ◽  
Volcano Eruption ◽  
Close Proximity ◽  
Global Navigation Satellite ◽  
Sarychev Peak

Global Navigation Satellite Systems have been extensively used to investigate the ionosphere response to various natural and man-made phenomena for the last three decades. However, ionospheric reaction to volcano eruptions is still insufficiently studied and understood. In this work we analyzed the ionospheric response to the 11–16 June 2009 VEI class 4 Sarychev Peak volcano eruption by using surrounding Russian and Japanese GPS networks. Prominent covolcanictotal electron content (TEC)ionospheric disturbances (CVIDs) with amplitudes and periods ranged between 0.03–0.15 TECU and 2.5–4.5 min were discovered for the three eruptive events occurred at 18:51 UT, 14 June; at 01:15 and 09:18 UT, 15 June 2009. The estimates of apparent CVIDs velocities vary within 700–1000 m/s in the far-field zone (300–900 km to the southwest from the volcano) and 1300–1800 m/s in close proximity toSarychev Peak. The characteristics of the observed TEC variations allow us to attribute them to acoustic mode. The south-southwestward direction is preferred for CVIDs propagation. We concluded that the ionospheric response to a volcano eruption is mainly determined by a ratio between explosion strength and background ionization level. Some evidence of secondary (F2-layer) CVIDs’ source eccentric location were obtained.

Could the Beirut Explosion perturb the Ionosphere? Pre-results Using TEC-GNSS observations.

2021 ◽  
Author(s):  
Mohamed Freeshah ◽  
Xiaohong Zhang ◽  
Erman Şentürk ◽  
Xiaodong Ren ◽  
Muhammad Arqim Adil ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Space Weather ◽  
Global Navigation Satellite Systems ◽  
Electron Content ◽  
Free Electrons ◽  
Total Electron ◽  
Satellite Systems ◽  
Underground Nuclear Explosions ◽  
Nuclear Explosions ◽  
Global Navigation Satellite

<p>Natural hazards such as shallow earthquakes and volcanic explosions are known to generate acoustic and gravity waves at infrasonic velocity to propagate in the atmosphere layers. These waves could induce the layers of the ionosphere by change the electron density based on the neutral particles and free electrons coupling. Recently, some studies have dealt with some manmade hazards such as buried explosions and underground nuclear explosions which could cause a trigger to the ionosphere. The Global Navigation Satellite Systems (GNSS) provide a good way to measure ionospheric total electron content (TEC) through the line of sight (LOS) from satellite to receiver. The carrier-to-code leveling (CCL) technique is carried out for each continuous arc where CCL eliminates potential ambiguity influence and it degrades the pseudo-range noise. Meanwhile, the CCL retains high precision in the carrier-phase. In this study, we focus on the Beirut Explosion on August 4, 2020, to check slant TEC (STEC) variations that may be associated with the blast of Beirut Port. The TECs were analyzed through the Morlet wavelet to check the possible ionospheric response to the blast. An acoustic‐gravity wave could be generated by the event which could disturb the ionosphere through coupling between solid earth-atmosphere-ionosphere during the explosion. To verify TEC disturbances are not associated with space weather, disturbance storm-time (Dst), and Kp indices were investigated before, during, and after the explosion. The steady-state of space weather before and during the event indicated that the observed variations of TEC sequences were caused by the ammonium nitrate explosion. There was a large initial explosion, followed by a series of smaller blasts, about ~30 seconds, a colossal explosion has happened, a supersonic blast wave radiating through Beirut City. As a result of the chemistry behind ammonium nitrate’s explosive, a mushroom cloud was sent into the air. We suggest that these different explosions in strength and time could be the reason for different time arrival of the detected ionospheric disturbances over GNSS ground-based stations.</p>

Ionosphere VTEC modeling with the raw-observation-based PPP model：an advantage demonstration in the multi-frequency and multi-GNSS context

2020 ◽  
Author(s):  
Teng Liu ◽  
Baocheng Zhang ◽  
Yunbin Yuan ◽  
Xiao Zhang
Keyword(s):  
Rapid Development ◽  
Global Navigation Satellite Systems ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Dual Frequency ◽  
International Gnss Service ◽  
Total Electron ◽  
Satellite Systems ◽  
Triple Frequency ◽  
Global Navigation Satellite

<p>The ionospheric delay accounts for one of the major errors that the Global Navigation Satellite Systems (GNSS) suffer from. Hence, the ionosphere Vertical Total Electron Content (VTEC) map has been an important atmospheric product within the International GNSS Service (IGS) since its early establishment. In this contribution, an enhanced method has been proposed for the modeling of the ionosphere VTECs. Firstly, to cope with the rapid development of the newly-established Galileo and BeiDou constellations in recent years, we extend the current dual-system (GPS/GLONASS) solution to a quad-system (GPS/GLONASS/Galileo/BeiDou) solution. More importantly, instead of using dual-frequency observations based on the Carrier-to-Code Leveling (CCL) method, all available triple-frequency signals are utilized with a general raw-observation-based multi-frequency Precise Point Positioning (PPP) model, which can process dual-, triple- or even arbitrary-frequency observations compatibly and flexibly. Benefiting from this, quad-system slant ionospheric delays can be retrieved based on multi-frequency observations in a more flexible, accurate and reliable way. The PPP model has been applied in both post-processing global and real-time regional VTEC modeling. Results indicate that with the improved slant ionospheric delays, the corresponding VTEC models are also improved, comparing with the traditional CCL method.</p>

scholarly journals MONITOR Ionospheric Network: two case studies on scintillation and electron content variability

2017 ◽  
Vol 35 (3) ◽  
pp. 377-391 ◽  
Author(s):  
Yannick Béniguel ◽  
Iurii Cherniak ◽  
Alberto Garcia-Rigo ◽  
Pierrick Hamel ◽  
Manuel Hernández-Pajares ◽  
...  
Keyword(s):  
Case Studies ◽  
Global Navigation Satellite Systems ◽  
Electron Content ◽  
Satellite Systems ◽  
First Case ◽  
Gnss Receivers ◽  
Recent Phase ◽  
Global Navigation Satellite ◽  
Gnss Data ◽  
High Frequency Sampling

Abstract. The ESA MONITOR network is composed of high-frequency-sampling global navigation satellite systems (GNSS) receivers deployed mainly at low and high latitudes to study ionosphere variability and jointly with global GNSS data and ionospheric processing software in support of the GNSS and its satellite-based augmentation systems (SBAS) like the European EGNOS. In a recent phase of the project, the network was merged with the CNES/ASECNA network and new receivers were added to complement the latter in the western African sector. This paper summarizes MONITOR, presenting two case studies on scintillations (using almost 2 years of data measurements). The first case occurred during the major St. Patrick's Day geomagnetic storm in 2015. The second case study was performed in the last phase of the project, which was supported by ESA EGNOS Project Office, when we paid special attention to extreme events that might degrade the system performance of the European EGNOS.

scholarly journals Three-dimensional data assimilation for ionospheric reference scenarios

2017 ◽  
Vol 35 (2) ◽  
pp. 203-215 ◽  
Author(s):  
Tatjana Gerzen ◽  
Volker Wilken ◽  
David Minkwitz ◽  
Mainul M. Hoque ◽  
Stefan Schlüter
Keyword(s):  
Data Assimilation ◽  
Three Dimensional ◽  
Model Space ◽  
Initial Guess ◽  
Global Navigation Satellite Systems ◽  
Background Model ◽  
Electron Content ◽  
Total Electron ◽  
Satellite Systems ◽  
Global Navigation Satellite

Abstract. The reliable estimation of ionospheric refraction effects is an important topic in the GNSS (Global Navigation Satellite Systems) positioning and navigation domain, especially in safety-of-life applications. This paper describes a three-dimensional ionosphere reconstruction approach that combines three data sources with an ionospheric background model: space- and ground-based total electron content (TEC) measurements and ionosonde observations. First the background model is adjusted by F2 layer characteristics, obtained from space-based ionospheric radio occultation (IRO) profiles and ionosonde data, and secondly the final electron density distribution is estimated by an algebraic reconstruction technique.The method described is validated by TEC measurements of independent ground-based GNSS stations, space-based TEC from the Jason 1 and 2 satellites, and ionosonde observations. A significant improvement is achieved by the data assimilation, with a decrease in the residual errors by up to 98 % compared to the initial guess of the background. Furthermore, the results underpin the capability of space-based measurements to overcome data gaps in reconstruction areas where less GNSS ground-station infrastructure exists.

scholarly journals Dual-parameter regularization method in three-dimensional ionospheric reconstruction

2018 ◽  
Vol 36 (5) ◽  
pp. 1255-1266
Author(s):  
Sicheng Wang ◽  
Sixun Huang ◽  
Hanxian Fang
Keyword(s):  
Regularization Method ◽  
Three Dimensional ◽  
Global Navigation Satellite Systems ◽  
Electron Content ◽  
Regularization Algorithm ◽  
Total Electron ◽  
Satellite Systems ◽  
Regularization Parameters ◽  
Global Navigation Satellite ◽  
Parameter Regularization

Abstract. Ionospheric tomography based on the total electron content (TEC) data along the ray path from Global Navigation Satellite Systems (GNSS) satellites to ground receivers is a typical ill-posed inverse problem. The regularization method is an effective method to solve this problem, which incorporates prior constraints to approximate the real ionospheric variations. When two or more prior constraints are used, the corresponding multiple regularization parameters are introduced in the cost functional. Assuming that the ionospheric spatial variations can be separable in the horizontal and vertical directions, different prior constraints are used in each direction, and the dual-parameter regularization algorithm is established to reconstruct the three-dimensional ionospheric electron density in the present paper. To make the reconstruction results comprehensively reflect the observation information and background (prior) information, it is crucial to determine the optimal regularization parameters. The linear model function method is used to choose these regularization parameters. Both an ideal test and a real test show that this regularization algorithm can effectively improve the background model output.

scholarly journals Tomography of the ionospheric electron density with geostatistical inversion

2015 ◽  
Vol 33 (8) ◽  
pp. 1071-1079 ◽  
Author(s):  
D. Minkwitz ◽  
K. G. van den Boogaart ◽  
T. Gerzen ◽  
M. Hoque
Keyword(s):  
Electron Density ◽  
Signal Propagation ◽  
Global Navigation Satellite Systems ◽  
Electron Content ◽  
Covariance Model ◽  
Spatial Covariance ◽  
Total Electron ◽  
Satellite Systems ◽  
Simple Kriging ◽  
Global Navigation Satellite

Abstract. In relation to satellite applications like global navigation satellite systems (GNSS) and remote sensing, the electron density distribution of the ionosphere has significant influence on trans-ionospheric radio signal propagation. In this paper, we develop a novel ionospheric tomography approach providing the estimation of the electron density's spatial covariance and based on a best linear unbiased estimator of the 3-D electron density. Therefore a non-stationary and anisotropic covariance model is set up and its parameters are determined within a maximum-likelihood approach incorporating GNSS total electron content measurements and the NeQuick model as background. As a first assessment this 3-D simple kriging approach is applied to a part of Europe. We illustrate the estimated covariance model revealing the different correlation lengths in latitude and longitude direction and its non-stationarity. Furthermore, we show promising improvements of the reconstructed electron densities compared to the background model through the validation of the ionosondes Rome, Italy (RO041), and Dourbes, Belgium (DB049), with electron density profiles for 1 day.

scholarly journals An SBAS Integrity Model to Overbound Residuals of Higher-Order Ionospheric Effects in the Ionosphere-Free Linear Combination

2020 ◽  
Vol 12 (15) ◽  
pp. 2467
Author(s):  
Stefan Schlüter ◽  
Mohammed Mainul Hoque
Keyword(s):  
Linear Combination ◽  
Global Navigation Satellite Systems ◽  
Vertical Position ◽  
Electron Content ◽  
Dual Frequency ◽  
Total Electron ◽  
Satellite Systems ◽  
Position Errors ◽  
Global Navigation Satellite ◽  
Ray Bending

The next generation of satellite-based augmentation systems (SBAS) will support aviation receivers that take advantage of the ionosphere-free dual-frequency combination. By combining signals of the L1 and L5 bands, about 99% of the ionospheric refraction effects on the GNSS (Global Navigation Satellite Systems) signals can be removed in the user receivers without additional SBAS corrections. Nevertheless, even if most of the negative impacts on GNSS signals are removed by the ionospheric-free combination, some residuals remain and have to be taken into account by overbounding models in the integrity computation conducted by safety-of-live (SoL) receivers in airplanes. Such models have to overbound residuals as well, which result from the most rare extreme ionospheric events, e.g., such as the famous “Halloween Storm”, and should thus include the tails of the error distribution. Their application shall lead to safe error bounds on the user position and allow the computation of protection levels for the horizontal and vertical position errors. Here, we propose and justify such an overbounding model for residual ionospheric delays that remain after the application of the ionospheric-free linear combination. The model takes into account second- and third-order ionospheric refraction effects, excess path due to ray bending, and increased ionospheric total electron content (TEC) along the signal path due to ray bending.

scholarly journals Finding the Ionospheric Fluctuations Reflection in the Pulsar Signals’ Characteristics Observed with LOFAR

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 51 ◽  
Author(s):  
Leszek P. Błaszkiewicz ◽  
Paweł Flisek ◽  
Kacper Kotulak ◽  
Andrzej Krankowski ◽  
Wojciech Lewandowski ◽  
...  
Keyword(s):  
Low Frequency ◽  
Global Navigation Satellite Systems ◽  
Electron Content ◽  
Radio Waves ◽  
Total Electron ◽  
Satellite Systems ◽  
Peak Flux ◽  
Global Navigation Satellite ◽  
Gnss Data ◽  
Main Factor

Pulsars’ signals reaching the atmosphere can be considered being stable under certain assumptions. In such a case the ionosphere remains the main factor distorting signal from the extraterrestrial sources, particularly if we observe them at long radio waves. In this article we present the results of the analysis of relative peak flux changes for two selected pulsars: PSR J0332+5434 (B0329+54) and PSR J1509+5531 (B1508+55), observed with the long radio wave sensor (The PL612 Low Frequency Array (LOFAR) station in Bałdy), together with the analysis of Rate of TEC (ROT) parameter changes measured with the Global Navigation Satellite Systems (GNSS) sensor (IGS LAMA station (IGS: International GSSN Service)). The main objective of the work is to find if the rapid plasma density (observed with the Rate of Total Electron Content (TEC)) has a counterpart in the pulsar observation characteristics. This focuses the attention on ionosphere influence during pulsar investigations at low radio frequencies. Additionally, what was the aim of this work, our results give reasons for using pulsar signals from LOFAR together with GNSS data as multi instrumental ionosphere state probes. Our results show a clear anti-correlation between the ROT and the pulsar profile’s peak flux trends.

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