Global Positioning System Satellites Research Articles

Analysis of Plasma Bubble Signatures in Total Electron Content Maps of the Low-Latitude Ionosphere: A Simplified Methodology

The ionosphere over the Brazilian region has particular characteristics due to the large geomagnetic declination angle over most of the territory. Furthermore, the equatorial ionization anomaly southern crest is located over the Brazilian territory. In this region, plasma irregularities may arise in the post-sunset hours. These ionospheric irregularities develop in the form of magnetic field-aligned plasma depletions, known as equatorial plasma bubbles, which may seriously affect radio signals that propagate through them. These irregularity structures can cause amplitude and phase scintillation of the propagating signals, thereby compromising the availability, performance, and integrity of satellite-based communication and navigation systems. Additionally, the total electron content (TEC) introduces propagation delays that can contribute to range measurement errors for global positioning system (GPS) users. The ionospheric characteristics change significantly according to the time of day, season, as well as the solar and geomagnetic activities, among other factors. Indeed, the ionosphere is one of the most significant sources of errors in the positioning and navigation systems based on the GPS satellites. Due to these features, there is a strong interest by the scientific community in better understanding and characterizing the ionospheric behavior. In this context, the TEC analysis has wide applicability for space plasma studies and is a well-established tool for investigating the ionospheric behavior and its potential impact on space-based navigation systems. One of the goals of these studies is the generation of TEC maps for a geographic region based on GPS observations. In the present work, some electrodynamic processes of the low-latitude ionosphere are reviewed and the TEC estimation based on GPS measurements is revisited in detail. A methodology aimed at creating the TEC maps is presented and validated by comparison with results from other geophysical instruments, such as all-sky imagers and ionosondes. Finally, examples of the ionospheric behavior displayed by TEC maps during equatorial plasma bubble events and a geomagnetic storm are fully described and discussed.

Estimation of GPS Differential Code Biases Based on Independent Reference Station and Recursive Filter

The differential code bias (DCB) of the Global Navigation Satellite Systems (GNSS) receiver should be precisely corrected when conducting ionospheric remote sensing and precise point positioning. The DCBs can usually be estimated by the ground GNSS network based on the parameterization of the global ionosphere together with the global ionospheric map (GIM). In order to reduce the spatial-temporal complexities, various algorithms based on GIM and local ionospheric modeling are conducted, but rely on station selection. In this paper, we present a recursive method to estimate the DCBs of Global Positioning System (GPS) satellites based on a recursive filter and independent reference station selection procedure. The satellite and receiver DCBs are estimated once per local day and aligned with the DCB product provided by the Center for Orbit Determination in Europe (CODE). From the statistical analysis with CODE DCB products, the results show that the accuracy of GPS satellite DCB estimates obtained by the recursive method can reach about 0.10 ns under solar quiet condition. The influence of stations with bad performances on DCB estimation can be reduced through the independent iterative reference selection. The accuracy of local ionospheric modeling based on recursive filter is less than 2 Total Electron Content Unit (TECU) in the monthly median sense. The performance of the recursive method is also evaluated under different solar conditions and the results show that the local ionospheric modeling is sensitive to solar conditions. Moreover, the recursive method has the potential to be implemented in the near real-time DCB estimation and GNSS data quality check.

Global Prompt Proton Sensor Network: Monitoring Solar Energetic Protons Based on GPS Satellite Constellation

AbstractEnergetic particle instruments on board Global Positioning System (GPS) satellites form a powerful global prompt proton sensor network (GPPSn) that provides an unprecedented opportunity to monitor and characterize solar energetic protons targeting the Earth. The medium‐Earth orbits of the GPS constellation have the unique advantage of allowing solar energetic protons to be simultaneously measured from multiple points in both open‐ and closed‐field line regions. Examining two example intervals of solar proton events, we showcase in this study how GPS proton data are prepared, calibrated, and utilized to reveal important features of solar protons, including their source, acceleration/scattering by interplanetary shocks, the relative position of Earth when impinged by these shocks, the shape of solar particle fronts, the access of solar protons inside the dynamic geomagnetic field, and temporally varying proton distributions in both energy and space. By comparing to Van Allen Probes data, GPS proton observations are further demonstrated not only to be useful for qualitatively monitoring the dynamics of solar protons but also for quantitative scientific research including determining cutoff L‐shells. Our results establish that this GPPSn can join forces with other existing solar proton monitors and contribute to observing, warning, understanding, and ultimately forecasting the incoming solar energetic proton events.

Applying the matched-filter technique to the search for dark matter transients with networks of quantum sensors

There are several networks of precision quantum sensors in existence, including networks of atomic clocks, magnetometers, and gravitational wave detectors. These networks can be re-purposed for searches of exotic physics, such as direct dark matter searches. Here we explore a detection strategy for macroscopic dark matter objects with such networks using the matched-filter technique. Such “clumpy” dark matter objects would register as transients sweeping through the network at galactic velocities. As a specific example, we consider a network of atomic clocks aboard the Global Positioning System (GPS) satellites. We apply the matched-filter technique to simulated GPS atomic clock data and study its utility and performance. The analysis and the developed methodology have a discovery reach up to three orders of magnitude above the previous GPS results and have a wide applicability to other networks of quantum sensors.

Performance Evaluation of Troposphere Estimated from Galileo-Only Multi-Frequency Observations

The tropospheric delays estimated from the Global Navigation Satellite System (GNSS) have been proven to be an efficient product for monitoring variations of water vapor, which plays an important role in meteorology applications. The operational GNSS water vapor monitoring system is currently based on the Global Positioning System (GPS) and GLObal NAvigation Satellite System(GLONASS) dual-frequency observations. The Galileo satellite navigation system has been evolving continuously, and on 11 February 2019, the constellation reached 22 active satellites, achieving a capability of standalone Precise Point Positioning (PPP) and tropospheric estimation that is global in scope. This enhancement shows a 37% improvement if the precision of the Galileo-only zenith tropospheric delay, while we may anticipate further benefits in terms of tropospheric gradients and slant delays in the future if an optimal multi-constellation and multi-frequency processing strategy is used. First, we analyze the performance of the multi-frequency troposphere estimates based on the PPP raw observation model by comparing it with the standard ionosphere-free model. The performance of the Galileo-only tropospheric solution is then validated with respect to GPS-only solution using 48 globally distributed Multi-GNSS Experiment (MGEX) stations. The averaged bias and standard deviations are −0.3 and 5.8 mm when only using GPS satellites, respectively, and 0.0 and 6.2 mm for Galileo, respectively, when compared to the International GNSS Service (IGS) final Zenith Troposphere Delay(ZTD) products. Using receiver antenna phase center corrections from the corresponding GPS dual-frequency observations does not affect the Galileo PPP ambiguity float troposphere solutions. These results demonstrate a comparable precision achieved for both Galileo-only and GPS-only ZTD solutions, however, horizontal tropospheric gradients, estimated from standalone GPS and Galileo solutions, still show larger discrepancies, mainly due to their being less Galileo satellites than GPS satellites. Including Galileo E1, E5a, E5b, and E5 signals, along with their proper observation weighting, show the benefit of multi-frequency observations, further improving the ZTD precision by 4% when compared to the dual-frequency raw observation model. Overall, the presented results demonstrate good prospects for the application of multi-frequency Galileo observations for the tropospheric parameter estimates.

Spatial ecology of non-breeding Eurasian Griffon Vultures Gyps fulvus in relation to natural and artificial food availability

ABSTRACT Capsule: The movements and spatial ecology of non-breeding Eurasian Griffon Vultures Gyps fulvus in northern Italy, Croatia and Austria do not seem to be affected by feeding station use. Aims: The purpose of this study was to assess how the creation of a feeding station at the Riserva Naturale Regionale del Lago di Cornino (Forgaria nel Friuli, northeast Italy) during the 1980s might have affected the spatial and behavioural ecology of the Eurasian Griffon Vulture. Methods: Using global positioning system (GPS) satellite tracking, we studied movements of nine non-breeding Eurasian Griffon Vultures within the Riserva Naturale Regionale del Lago di Cornino in Italy, the Hohe Tauern in Austria and the Kvarner Gulf in Croatia. Results: Both the average foraging range size and the time spent by the birds in Italy were comparable to those recorded in Croatia and Austria, where the vultures depend on unpredictable food resources. A significant difference in terms of foraging range size was recorded among seasons. In winter it seems to be smaller as a consequence of reduced movements performed by the individuals due to harsh climate conditions. Conclusions: Our results suggest that the creation of a feeding station in Forgaria does not seem to have affected the spatial ecology of the Eurasian Griffon Vulture. However, due to the limited sample size and the young age of the individuals monitored, which have a long dispersal period, the findings presented should be considered as preliminary. Further research needs to be implemented to inform decisions regarding the management of supplementary feeding stations to promote the recovery and conservation of scavenger species, particularly in areas in which they have declined massively.

Forecasting of ionospheric TEC for different latitudes, seasons and solar activity conditions based on OKSM

Ionosphere is the upper atmosphere region that contains sufficient number of electrons which disturb the propagation of radio signal travel from navigational satellite to ground/user receiver. Ionospheric delay in range measurement is related to its Total Electron Content (TEC). Ionospheric delay results in range error and degrades the user position accuracy of navigational satellite systems such as Global Positioning System (GPS) and Indian Regional Navigational Satellite System (IRNSS). Hence a suitable TEC prediction model to correct the range delay in single frequency range measurement is necessary. In dual frequency receiver, ionospheric delay is estimated and eliminated using the two range measurements performed at the same time. This paper describes the TEC prediction methodology using Ordinary Kriging based Surrogate Model (OKSM). OKSM is evaluated using the data received and collected from the IRNSS receiver station installed at ACS College of Engineering (ACSCE), Bengaluru (12.8913 °N, 77.4658 °E), India and other International GNSS Service (IGS) network stations. IRNSS TEC data (January 2018) is calculated by using dual frequency (L5 & S) pseudo range method and TEC is smoothed by normal cubic smoothing spline method. IRNSS Vertical TEC (VTEC) is predicted from 16 January 2018 to 26 January 2018 by using previous six days of estimated VTEC values. Similarly, GPS VTEC for IGS station at IISC, Bengaluru is also predicted for same duration to validate the developed OKSM. In order to evaluate the performance of the developed forecasting model for different geographic locations, solar activity conditions and seasons, the VTEC is predicted and analyzed for different latitude regions such as low-latitude PHON station (6.9599 °N, 158.2101 °E), mid-latitude ALGO station (45.9588 °N, −78.0714 °E) and high-latitude NRIL station (69.3618 °N, 88.3597 °E) during different solar activity conditions (Low-2008, Medium-2011 and High-2013 solar activity) and during different seasons (spring, summer, rainy and winter) in the year 2017. From the analysis of OKSM prediction results, it is observed that, RMSE of predicted TEC varies from 0.79 to 3.6 TECU, MAE is 0.4 to 3 TECU and MAPE is within 40% for ionospheric quiet days. VTEC is also predicted during storm days (26 October 2003 to 31 October 2003). To study the performance of the model, VTEC prediction results of OKSM are compared with prediction results from Standard Persistence Model (SPM) and VTEC derived from International Reference Ionosphere (IRI-2016) model. The RMSE of OKSM is 1.9679 TECU, MAE is 1.245 TECU and MAPE is 9%, whereas for SPM, RMSE is 4.8372 TECU, MAE is 3.7496 TECU and MAPE is 36%. Similarly, for IRI-2016 model, RMSE is 7.9 TECU, MAE is 7.1976 TECU and MAPE is 66%. Therefore, TEC predictions by OKSM are better than SPM and IRI-2016. The results show that the OKSM is useful for applications in ionospheric studies.

A Vehicle Tracking System Using Greedy Forwarding Algorithms for Public Transportation in Urban Arterial

A vehicle tracking system assists public transportation users in their movements by providing real-time information on the locations of vehicles in transit. Public transportation in parts of developing nations, especially Nigeria is ineffective. The system is chaotic and frustrating, especially at peak traffic periods. In a bid to address the problem, a vehicle tracking system was developed as a component of an Advanced Public Transportation System to improve commuting in an urban arterial. The developed system is based on wireless technologies of the Global Positioning System (GPS) and Global System for Mobile Communication module. It records and displays real-time vehicle location using a GPS-based greedy forwarding algorithm, computes route distance information using distance-time based algorithm and radar range sensor (RRS). A pseudo-range mathematical model using the Haversine formula was adopted in determining the accurate position of an object during signal transmission from GPS satellites to the receiver message module. The minimum inversion matrix method was used for the GPS-based geometric dilution of precision (GDoP) selection of satellite approximation and distance. Atmega328P controller chip was used as the logical control unit for processing activities in the tracking system and programming in Arduino IDE using C-language. The system was deployed to a university transportation system in Nigeria: a journey to and from the Bosso and Gidan Kwano Campuses route in the Federal University of Technology, Minna. The vehicle tracking system was tested with 11 tracked satellite and minor dilution error (PDoP error = 1.9, HDoP=0.9, and VDOP=1.7) was recorded. The system is efficient and accurate in distance and time information display with a minor delay. The system would enhance fleet management schemes for urban arterial and can be adopted universally.

Counterexample and example of the principle of relativity

In the Earth-centered locally inertial coordinate system, the Principle of Relativity is not satisfied when using the experimental data of the global positioning system (GPS). The clocks in the GPS satellites tick off time more slowly by the velocity v G = 4 km/s after elimination of the gravitational effects. Between two local gravity fields, the Principle of Relativity is satisfied.

Ionospheric induced plasma disturbances afore the m7.9 eastern Sichuan china earthquake of 12th may, 2008

A great number of earthquakes occur yearly in different areas and almost 100 -120 of them have a magnitude above 5. These seismic activities are very harmful for the inhabitants. Findings reveal that this seismo-electro-magnetic abnormality is a mirror image of some processes, which originated a few weeks before the main event and stay until few days after it. Plasma ion analyser (IAP) and Instrument Sonde de Langmuir (ISL) sensors) experiments available on Detection of Electromagnetic Emissions Transmitted from Earthquake Regions (DEMETER) and Total Electron Content (TEC) from Global Positioning System (GPS) satellites, were employed to study the variations of electron and ion density for ionospheric disturbances before the M7.9 Eastern Sichuan China earthquake of 12th May, 2008. The study revealed seismo-ionospheric induced perturbations exactly three weeks afore the earthquake in all four investigated parameters. Electron density recorded 16.94 cm-3, electron temperature revealed - 2.25 o C while total ion density displayed 6.57 cm-1. The total electron content ranged from 4.28 to 3.6. The disturbance storm time (Dst) and planetary 3-hourly range (Kp) indices were used to classify pre-earthquake anomalies from the other anomalies associated with geomagnetic activities and was seen that this day (-21days relative to the earthquake) was devoid of geomagnetic storm, thus the observed perturbations were seismo-induced but not geomagnetic induced.

Spatio-Temporal Prediction of Ionospheric Total Electron Content Using an Adaptive Data Fusion Technique

The ionosphere, a part of upper atmosphere, plays an important role on the propagation of radio waves. Hence, understanding, remote sensing and monitoring of the ionospheric phenomena can provide a compressive description to the physical process that are affected by the behavior of ionosphere. One of descriptive quantity of ionosphere is Total Electron Content (TEC). TEC is the total number of electrons integrated between two points and characterized by observing carrier phase delays of received radio signals transmitted from satellites located above the ionosphere, often using Global Positioning System (GPS) satellites. In this study, TEC is predicted from TEC estimates obtained from GPS network located in Turkey in space and time using an Adaptive Data Fusion Technique (ADF). It is observed that characteristic distributions of the predict TEC and original TEC values are similar with each other. Mean Square Errors are less than 4 TECU. ADF has a high performance for the spatio-temporal prediction when the results are compared with the techniques used in the related studies in the literature.

Computing GPS satellite velocity and acceleration from the broadcast navigation message

We present an extension to the Global Positioning System (GPS) broadcast navigation message user equations for computing GPS space vehicle (SV) velocity and acceleration. Although similar extensions have been published, the extension presented herein includes a distinct kinematic method for computing SV acceleration, which significantly reduces the complexity of the equations and improves the mean magnitude results by approximately one order of magnitude by including oblate Earth perturbation effects. Additionally, detailed analyses and validation results using multiple days of precise ephemeris data and multiple broadcast navigation messages are presented. Improvements in the equations for computing SV position are also included, removing ambiguity and redundancy in the existing user equations. The recommended changes make the user equations more complete and more suitable for implementation in a wide variety of programming languages employed by GPS users. Furthermore, relativistic SV clock error rate computation is enabled by the recommended equations. A complete, stand-alone table of the equations in the format and notation of the GPS interface specification is provided, along with benchmark test cases to simplify implementation and verification.

Efficiency research of signal recovery algorithms with long gaps and rare arrival of measurements

Subject of Research. Efficiency study of cameral signal recovery algorithms is carried out in the presence of single long gaps and rare arrival of measurements. Quantitative comparison of the algorithms is performed by modeling and cameral processing of satellite navigation receiver real solutions. The standard error is an algorithm measure of efficiency. Method. The algorithm is considered based on a quadratic model taking into account constraints on the signal size and its derivative. The algorithm is known from the literature, however, it is used for the first time in satellite navigation problems. Moreover, comparison is made with the other two algorithms: quadratic approximation without regard to constraints and linear interpolation. Main Results. After analyzing the results, the following recommendations have been developed on the use of recovery algorithms in order to achieve the minimum mean square error of recovery. It is established that the quadratic approximation with constraints is the best of the considered algorithms in terms of accuracy; however, when recovering the signal during the long-term measurement absence at the beginning and at the end of the gap, it is better to use linear interpolation. In order to achieve the minimum standard error in the central part of the gap, it is recommended to use the algorithm with constraints and break down a fragment of the processed measurement implementation so that no more than one polynomial interval junction of the restored signal is located on the measurement absence section. For short measurement intervals to the left and to the right of the gap, the best option is to split the implementation fragment into 2 intervals. In case of the signal restoration under conditions of rarely received measurements, it is advisable to choose the interval duration of the polynomial representation less than the period of measurement discreteness. Practical Relevance. The application of the developed algorithms can improve the positioning accuracy for the users of global-positioning satellite systems, however, their application area may be more extensive and include post-processing of field measurements in geodesy and mapping tasks.

3D Grid-based Global Positioning System Satellite Signal Shadowing Range Modeling in Urban Area

3D Grid-based Global Positioning System Satellite Signal Shadowing Range Modeling in Urban Area

Positioning performance analysis on combined GPS/BDS precise point positioning

Combining the observation data from five Multi-GNSS Experiment (MGEX) stations with the precise orbit and clock products from Global Positioning System (GPS) and BeiDou Navigation Satellite System (BDS), we studied the model of combined GPS/BDS precise point positioning, and then analyzed the convergence speed and short-time (6 h) positioning accuracy. The calculation results show that in static positioning, the average convergence time of GPS is about 50 min, and its horizontal accuracy is better than 2 cm while the vertical accuracy is better than 4 cm. The convergence speed of combined GPS/BDS is about 40 min, and its positioning accuracy is close to that of GPS. In kinematic positioning, the average convergence time of GPS is about 72 min, and its horizontal accuracy is better than 5 cm while the vertical accuracy is better than 12 cm. The average convergence time of GPS/BDS is about 57 min, and its horizontal accuracy is better than 3 cm while the vertical accuracy is better than 9 cm. Combined GPS/BDS has significantly improved the convergence speed, and its positioning accuracy is slightly than that of GPS.

Unmodeled error mitigation for single-frequency multi-GNSS precise positioning based on multi-epoch partial parameterization

In global navigation satellite system (GNSS) precise positioning, some residual systematic errors inevitably exist in GNSS observations. These residual systematic errors can be regarded as the unmodeled errors that cannot be easily mitigated by traditional parameterization, modeling or other methods, mainly due to their spatiotemporal complexity. In a multi-GNSS scenario, there are enough redundant observations to reveal the unmodeled errors to a great extent, according to the behaviors of observation residuals. However, in the case of single frequency, the first-order ionospheric delays cannot be eliminated by the ionosphere-free combination in terms of two or more carrier phases with different frequencies, thus resulting in significant unmodeled effects more frequently. We therefore propose a method for real-time mitigation of the unmodeled errors in single-frequency multi-GNSS precise positioning. The proposed method has two main aspects. First, considering the estimability and property of unmodeled error parameters, the method of multi-epoch partial parameterization is proposed. Second, an iterative procedure is given, which can be applied in real time. The experiment is conducted using a four-station network of real single-frequency and combined global positioning system (GPS) and BeiDou navigation satellite system (BDS) observations, with baseline lengths from approximately 5 to 25 km. The results show that the GPS/BDS unmodeled errors are indeed mitigated and the positioning precision is improved after using the proposed method, where the precision of the up direction can be improved by a maximum of 56.90%.

Estimation of forest leaf area index and clumping index from the Global Positioning System (GPS) satellite carrier-to-noise-density ratio (C/N0)

ABSTRACTForest leaf area index (LAI) and clumping index (CI) are critical structural parameters to study the biomass, biogeochemical cycles, ecological simulation, and radiation transfer in a forest system. The ground-based measurements by traditional methods are costly, time-consuming, and are sensitive to variations in solar illumination conditions. Global Positioning System (GPS) satellites transfer L-band signals, and the presence of the forest canopy leads to an increase in noise. The GPS satellite’s signal strength is generally described by the carrier-to-noise-density ratio (C/N0). This study explores the potential of using the GPS satellite C/N0 to estimate forest canopy structural parameters. We performed experiments at 16 forest plots in northeastern China. LAI, CI, and canopy closure were estimated by digital hemispherical photography (DHP) using the CAN_EYE software. The GPS satellite C/N0 was recorded with a modified smartphone application, GPSTest. The relationship between the forest canopy structural parameters and satellite C/N0 was analyzed for those observations with satellite elevation angle (SEA) > 30°. The results show that both the true LAI and the effective LAI have strong linear and polynomial correlation with C/N0 and the coefficient of determination (R2) is larger than 0.7. CI is linearly related to C/N0(R2 = 0.56). The linear relationship between the canopy closure and C/N0 is much lower (R2= 0.28). Accounting for the SEA effect, LAI can be estimated with R2 > 0.8, and CI with R2 = 0.6. LAI and CI can be well estimated from C/N0 when the SEA effect is accounted for. In general, the GPS C/N0 provides an alternative method to estimate forest canopy structural parameters.

On the transformation of the coordinates of points from the SK-42 system to WGS-84

The significant and effective use of global positioning satellite systems for solution of important theoretical and applied problems of Earth sciences means the preserving of the possibility to use a huge quantity of geodetic, cartographic, gravimetric and other data created on the basis of traditional methods and in different referencing coordinate systems. It is impossible without the correct coordinate transformation at the transition from one system to another. The determination of the coordinates of points using the satellite radio navigation system NAVSTAR GPS is closely related to the world geodetic coordinate system WGS-84. At the same time, data on gravity observations within the Pulkovo 1942 coordinate system have been accumulated in large volumes. It is obvious the need for recalculation of coordinates given in different systems. Information is given on the coordinate systems, geodetic coordinates, units of measurement, display formats for latitude and longitude values. The reference coordinate system of Pulkovo 1942 and the modern world geodetic system WGS-84 are described in sufficient detail. Formulas are given for calculating the normal gravity in these systems. Historical background and classification of coordinate transformation methods are considered. Significant role is given to the high-precision method of Molodensky and the modified Helmert method of coordinate transformation. The standard method of Molodensky is described at the level it is described in official open reports of US government agencies. Programs are considered that automate the solution of the problem of recalculating the coordinates of objects, as well as the issues of transformation of coordinate systems in geographical information systems. The attention is focused on the rash use of the software that might lead to some very strange and inexplicable results.

GPS-PWV Based Improved Long-Term Rainfall Prediction Algorithm for Tropical Regions

Global positioning system (GPS) satellite delay is extensively used in deriving the precipitable water vapor (PWV) with high spatio–temporal resolution. One of the recent applications of GPS derived PWV values are to predict rainfall events. In the literature, there are rainfall prediction algorithms based on GPS-PWV values. Most of the algorithms are developed using data from temperate and sub-tropical regions. Mostly these algorithms use maximum PWV rate, maximum PWV variation and monthly PWV values as a criterion to predict the rain events. This paper examines these algorithms using data from the tropical stations and proposes the use of maximum PWV value for better prediction. When maximum PWV value and maximum rate of increment criteria are implemented on the data from the tropical stations, the false alarm ( F A ) rate is reduced by almost 17% as compared to the results from the literature. There is a significant reduction in F A rates while maintaining the true detection ( T D ) rates as high as that of the literature. A study done on the varying historical length of data and lead time values shows that almost 80% of the rainfall can be predicted with a false alarm of 26.4 % for a historical data length of 2 hours and a lead time of 45 min to 1 hour.

Short‐ and Long‐Wavelength TIDs Generated by the Great American Eclipse of 21 August 2017

AbstractOn the 21 August 2017 the eclipse shadow drastically changed the state of the ionosphere over the United States. This effect on the ionosphere is visible in the total electron content measured by Global Navigation Satellite Systems (GNSS). The shadow moved with the supersonic speed of ~1,000 m/s over Oregon to ~650 m/s over South Carolina. In order to exhaustively explore the ionospheric signature of the eclipse, we use data of total electron content from ~3,000 GNSS stations seeing multiple Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) satellites to visualize the phenomena. This tremendous dataset allows high‐resolution characterization of the frequency content and wavelengths—using an omega‐k analysis based on 3‐D fast Fourier transform—of the eclipse signature in the ionosphere in order to fully identify traveling ionospheric disturbances (TIDs). We confirm the generation of TIDs associated with the eclipse including TIDs interpreted as bow waves in previous studies. Additionally, we reveal, for the first time, short (50–100 km) and long (500–600 km) wavelength TIDs with periods between 30 and 65 min. The sources of the revealed short wavelength TIDs are co‐located with the regions of stronger gradient of the EUV related to sunspots. Our work confirms and describes physical properties of the waves observable in the ionosphere during the Great American Eclipse.