scholarly journals MSTIDs impact on GNSS observations and its mitigation in rapid static positioning at medium baselines

2016 ◽  
Vol 58 (6) ◽  
Author(s):  
Rafal Sieradzki ◽  
Jacek Paziewski
Keyword(s):  
Electron Content ◽  
Ionospheric Disturbances ◽  
Relative Positioning ◽  
Total Electron ◽  
Satellite Positioning ◽  
Phase Data ◽  
And Performance ◽  
Rapid Static Positioning ◽  
The Impact ◽  
Gnss Observations

<p>Total electron content (TEC) fluctuation in the ionosphere is one of the main unresolved problems degrading ambiguity resolution and thus affect the reliability of satellite positioning. With regard to conditions prevailing at mid-latitudes, the impact of the upper atmospheric layers is primarily associated with the occurrence of medium-scale traveling ionospheric disturbances (MSTIDs). This study contains the combined analysis involving MSTIDs patterns observed in raw phase data and their impact on rapid static positioning. The first part is aimed at discrepancies in wavelike MSTIDs signatures detected in time series of high elevated measurements. It was demonstrated that the differences in slant ionospheric delays at medium baselines often exceed 0.5 TEC units and more importantly, the detected MSTIDs patterns were highly mutable. The next section presents the impact of MSTIDs on double differenced ionospheric delays and performance of rapid static positioning. The positioning was executed using two approaches. The first one adopted as a benchmark strategy was the geometry-based relative positioning model with weighted ionosphere and troposphere parametrization. The second approach was the improved version of the former. It used the rate of TEC corrections, which allowed the mitigation of MSTIDs through the reduction of epoch-wise ionospheric delays to one parameter for each double-differenced arc. The comparison of results for both strategies indicated significant improvement of positioning performance after the application of proposed algorithm.</p>

scholarly journals Ionospheric Responses to the June 2015 Geomagnetic Storm from Ground and LEO GNSS Observations

2020 ◽  
Vol 12 (14) ◽  
pp. 2200
Author(s):  
Chao Gao ◽  
Shuanggen Jin ◽  
Liangliang Yuan
Keyword(s):  
Geomagnetic Storm ◽  
Geomagnetic Storms ◽  
Low Earth Orbit ◽  
Horizontal Gradient ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Total Electron ◽  
Leo Satellites ◽  
The Impact ◽  
Gnss Observations

Geomagnetic storms are extreme space weather events, which have considerable impacts on the ionosphere and power transmission systems. In this paper, the ionospheric responses to the geomagnetic storm on 22 June 2015, are analyzed from ground-based and satellite-based Global Navigation Satellite System (GNSS) observations as well as observational data of digital ionosondes, and the main physical mechanisms of the ionospheric disturbances observed during the geomagnetic storm are discussed. Salient positive and negative storms are observed from vertical total electron content (VTEC) based on ground-based GNSS observations at different stages of the storm. Combining topside observations of Low-Earth-Orbit (LEO) satellites (GRACE and MetOp satellites) with different orbital altitudes and corresponding ground-based observations, the ionospheric responses above and below the orbits are studied during the storm. To obtain VTEC from the slant TEC between Global Positioning System (GPS) and LEO satellites, we employ a multi-layer mapping function, which can effectively reduce the overall error caused by the single-layer geometric assumption where the horizontal gradient of the ionosphere is not considered. The results show that the topside observations of the GRACE satellite with a lower orbit can intuitively detect the impact caused by the fluctuation of the F2 peak height (hmF2). At the same time, the latitude range corresponding to the peak value of the up-looking VTEC on the event day becomes wider, which is the precursor of the Equatorial Ionization Anomaly (EIA). However, no obvious response is observed in the up-looking VTEC from MetOp satellites with higher orbits, which indicates that the VTEC responses to the geomagnetic storm mainly take place below the orbit of MetOp satellites.

scholarly journals 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

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.

scholarly journals Detecting Ionospheric TEC Disturbances by Three Methods of Detrending through Dense CORS During A Strong Thunderstorm

2020 ◽  
Vol 63 (6) ◽  
Author(s):  
Mohamed Freeshah ◽  
Xiaohong Zhang ◽  
Jun Chen ◽  
Zhibo Zhao ◽  
Nahed Osama ◽  
...  
Keyword(s):  
Sampling Rate ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Average Difference ◽  
Short Term ◽  
Wuhan City ◽  
Total Electron ◽  
Research Findings ◽  
Communications System ◽  
Gnss Observations

Satellite navigation and communications system can substantially be disturbed by ionospheric perturbations. Consequently, monitoring ionospheric anomalous has great significance. In this study, we focus on the short-term irregular disturbances through a strong thunderstorm in Wuhan City, Hubei, China by using ground-based GNSS observations from dense Continuously Operating Reference Stations (CORS) with a sampling rate of 1s. The total electron content (TEC) was used to find possible perturbations after biases have been calibrated for the derived TEC. Additionally, the geomagnetic conditions and the state of solar radiation was checked in the study period to recognize the causes for the ionospheric disturbances. The maxima and minima values of TEC deviations were ~2.5 and 0.5 TECU, respectively. Three methods of Detrended Fluctuations Analysis (DFA) were applied to assess the ionospheric disturbances over GNSS CORS stations; “Multi-step numerical difference”(MSND), “6th order polynomials fitting” (PF), and “one-week average difference”(AD). The analyzed results showed that MSND has the lowest performance. Meanwhile, the fitted TEC data with 6th order polynomials technique presented an improvement and a discrepancy related to MSND. To resolve this discrepancy, we proposed AD technique, it accomplished the best performance related to the TEC disturbances and was compared with the other two techniques. The research findings showed that ionospheric disturbed electrons can be generated with various rates and different velocities through lightning influences.

scholarly journals Characterization of multi-scale ionospheric irregularities using ground-based and space-based GNSS observations

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
YuXiang Peng ◽  
Wayne A Scales ◽  
Michael D Hartinger ◽  
Zhonghua Xu ◽  
Shane Coyle
Keyword(s):  
Formation Flying ◽  
Satellite System ◽  
Ionospheric Irregularities ◽  
Mission Design ◽  
Electron Content ◽  
Total Electron ◽  
Spatial And Temporal Scales ◽  
Multi Scale ◽  
Global Navigation Satellite ◽  
Gnss Observations

AbstractIonospheric irregularities can adversely affect the performance of Global Navigation Satellite System (GNSS). However, this opens the possibility of using GNSS as an effective ionospheric remote sensing tool. Despite ionospheric monitoring has been undertaken for decades, these irregularities in multiple spatial and temporal scales are still not fully understood. This paper reviews Virginia Tech’s recent studies on multi-scale ionospheric irregularities using ground-based and space-based GNSS observations. First, the relevant background of ionospheric irregularities and their impact on GNSS signals is reviewed. Next, three topics of ground-based observations of ionospheric irregularities for which GNSS and other ground-based techniques are used simultaneously are reviewed. Both passive and active measurements in high-latitude regions are covered. Modelling and observations in mid-latitude regions are considered as well. Emphasis is placed on the increased capability of assessing the multi-scale nature of ionospheric irregularities using other traditional techniques (e.g., radar, magnetometer, high frequency receivers) as well as GNSS observations (e.g., Total-Electron-Content or TEC, scintillation). Besides ground-based observations, recent advances in GNSS space-based ionospheric measurements are briefly reviewed. Finally, a new space-based ionospheric observation technique using GNSS-based spacecraft formation flying and a differential TEC method is demonstrated using the newly developed Virginia Tech Formation Flying Testbed (VTFFTB). Based on multi-constellation multi-band GNSS, the VTFFTB has been developed into a hardware-in-the-loop simulation testbed with external high-fidelity global ionospheric model(s) for 3-satellite formation flying, which can potentially be used for new multi-scale ionospheric measurement mission design.

scholarly journals Statistical study of medium-scale traveling ionospheric disturbances in low-latitude ionosphere using an automatic algorithm

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Pin-Hsuan Cheng ◽  
Charles Lin ◽  
Yuichi Otsuka ◽  
Hanli Liu ◽  
Panthalingal Krishanunni Rajesh ◽  
...  
Keyword(s):  
Climate Model ◽  
Geomagnetic Latitude ◽  
Detection Algorithm ◽  
Support Vector ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Low Latitude ◽  
Total Electron ◽  
Medium Scale ◽  
Traveling Ionospheric Disturbances

AbstractThis study investigates the medium-scale traveling ionospheric disturbances (MSTIDs) statistically at the low-latitude equatorial ionization anomaly (EIA) region in the northern hemisphere. We apply the automatic detection algorithm including the three-dimensional fast Fourier transform (3-D FFT) and support vector machine (SVM) on total electron content (TEC) observations, derived from a network of ground-based global navigation satellite system (GNSS) receivers in Taiwan (14.5° N geomagnetic latitude; 32.5° inclination), to identify MSTID from other waves or irregularity features. The obtained results are analyzed statistically to examine the behavior of low-latitude MSTIDs. Statistical results indicate the following characteristics. First, the southward (equatorward) MSTIDs are observed almost every day during 0800–2100 LT in Spring and Winter. At midnight, southward MSTIDs are more discernible in Summer and majority of them are propagating from Japan to Taiwan. Second, northward (poleward) MSTIDs are more frequently detected during 1200–2100 LT in Spring and Summer with the secondary peak of occurrence between day of year (DOY) 100–140 during 0000–0300 LT. The characteristics of the MSTIDs are interpreted with additional observations from radio occultation (RO) soundings of FORMOSAT-3/COSMIC as well as modeled atmospheric waves from the high-resolution Whole Atmosphere Community Climate Model (WACCM) suggesting that the nighttime MSTIDs in Summer is likely connected to the atmospheric gravity waves (AGWs).

scholarly journals Estimation and Analysis of GNSS Differential Code Biases (DCBs) Using a Multi-Spacing Software Receiver

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 443
Author(s):  
Ye Wang ◽  
Lin Zhao ◽  
Yang Gao
Keyword(s):  
Primary Source ◽  
Intermediate Frequency ◽  
Global Navigation Satellite Systems ◽  
Electron Content ◽  
Software Receiver ◽  
International Gnss Service ◽  
Total Electron ◽  
Satellite Systems ◽  
Differential Code Biases ◽  
Gnss Observations

In the use of global navigation satellite systems (GNSS) to monitor ionosphere variations by estimating total electron content (TEC), differential code biases (DCBs) in GNSS measurements are a primary source of errors. Satellite DCBs are currently estimated and broadcast to users by International GNSS Service (IGS) using a network of GNSS hardware receivers which are inside structure fixed. We propose an approach for satellite DCB estimation using a multi-spacing GNSS software receiver to analyze the influence of the correlator spacing on satellite DCB estimates and estimate satellite DCBs based on different correlator spacing observations from the software receiver. This software receiver-based approach is called multi-spacing DCB (MSDCB) estimation. In the software receiver approach, GNSS observations with different correlator spacings from intermediate frequency datasets can be generated. Since each correlator spacing allows the software receiver to output observations like a local GNSS receiver station, GNSS observations from different correlator spacings constitute a network of GNSS receivers, which makes it possible to use a single software receiver to estimate satellite DCBs. By comparing the MSDCBs to the IGS DCB products, the results show that the proposed correlator spacing flexible software receiver is able to predict satellite DCBs with increased flexibility and cost-effectiveness than the current hardware receiver-based DCB estimation approach.

Implications of Ionospheric Scintillation for GNSS Users in Northern Europe

2005 ◽  
Vol 58 (2) ◽  
pp. 241-256 ◽  
Author(s):  
Marcio Aquino ◽  
Terry Moore ◽  
Alan Dodson ◽  
Sam Waugh ◽  
Jock Souter ◽  
...  
Keyword(s):  
Northern Europe ◽  
Ionospheric Scintillation ◽  
Electron Content ◽  
Total Electron ◽  
Northern European ◽  
Amplitude Fluctuations ◽  
The Uk ◽  
Time Delay Effect ◽  
Electron Density Irregularities ◽  
The Impact

Extensive ionospheric scintillation and Total Electron Content (TEC) data were collected by the Institute of Engineering Surveying and Space Geodesy (IESSG) in Northern Europe during years of great impact of the solar maximum on GNSS users (2001–2003). The ionospheric TEC is responsible for range errors due to its time delay effect on transionospheric signals. Electron density irregularities in the ionosphere, occurring frequently during these years, are responsible for (phase and amplitude) fluctuations on GNSS signals, known as ionospheric scintillation. Since June 2001 four GPS Ionospheric Scintillation and TEC Monitor receivers (the NovAtel/AJ Systems GSV4004) have been deployed at stations in the UK and Norway, forming a Northern European network, covering geographic latitudes from 53° to 70° N approximately. These receivers compute and record GPS phase and amplitude scintillation parameters, as well as TEC and TEC variations. The project involved setting up the network and developing automated archiving and data analysis strategies, aiming to study the impact of scintillation on DGPS and EGNOS users, and on different GPS receiver technologies. In order to characterise scintillation and TEC variations over Northern Europe, as well as investigate correlation with geomagnetic activity, long-term statistical analyses were also produced. This paper summarises our findings, providing an overview of the potential implications of ionospheric scintillation for the GNSS user in Northern Europe.

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