Data assimilation of ground GPS total electron content into a physics-based ionospheric model by use of the Kalman filter

Increasing the quality of ionosphere modeling is crucial and remains a challenge for many geodetic applications such as GNSS Precise Point Positioning (PPP) and navigation. Ionosphere models are the main tool to provide an estimation of Total Electron Content (TEC) to be corrected from GNSS career phase and pseudorange measurements. Skills of these models are however limited due to the simplifications in model equations and the imperfect knowledge of model parameters. In this study, an ionosphere reconstruction approach is presented, where global estimations of geodetic-based TEC measurements are combined with an ionospheric background model. This is achieved here through a novel simultaneous Calibration and Data Assimilation (C/DA) technique that works based on the sequential Ensemble Kalman Filter (EnKF). The C/DA method ingests the actual ionospheric measurements (derived from global GNSS measurements) into the IRI (International Reference Ionosphere) model. It also calibrates those parameters that control the F2 layer&#8217;s characteristics such as selected important CCIR (Comit&#233; Consultatif International des Radiocommunicationsand) URSI (International Union of Radio Science) coefficients.&#160; The calibrated parameters derived from the C/DA are then replaced in the IRI to simulate TEC values in locations, where less GNSS ground-station infrastructure exists, as well as to enhance the prediction of TEC when the observations are not available or their usage is cautious due to low quality. Our numerical assessments indicate the advantage of the C/DA to improve the IRI&#8217;s performance. Values of the TEC-Root Mean Square of Error (RMSE) are found to be decreased by up to 30% globally, compared to the original IRI simulations. The importance of the new TEC estimations is demonstrated for PPP applications, whose results show improvements in navigation applications.Keywords: Ionosphere, Calibration and Data Assimilation (C/DA), IRI, Total Electron Content (TEC), Precise Point Positioning (PPP), GNSS

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Global Ionospheric Model Accuracy Analysis Using Shipborne Kinematic GPS Data in the Arctic Circle

Remote Sensing ◽

10.3390/rs11172062 ◽

2019 ◽

Vol 11 (17) ◽

pp. 2062

Author(s):

Di Wang ◽

Xiaowen Luo ◽

Jinling Wang ◽

Jinyao Gao ◽

Tao Zhang ◽

...

Keyword(s):

Total Electron Content ◽

Satellite System ◽

The Arctic ◽

Electron Content ◽

Ionospheric Model ◽

International Gnss Service ◽

Total Electron ◽

Arctic Circle ◽

Analysis And Evaluation ◽

Ionospheric Models

The global ionospheric model built by the International Global Navigation Satellite System (GNSS) Service (IGS) using GNSS reference stations all over the world is currently the most widely used ionospheric product on a global scale. Therefore, analysis and evaluation of this ionospheric product’s accuracy and reliability are essential for the practical use of the product. In contrast to the traditional way of assessing global ionospheric models with ground-based static measurements, our study used shipborne kinematic global positioning system (GPS) measurements collected over 18 days to perform a preliminary analysis and evaluation of the accuracy of the global ionospheric models; our study took place in the Arctic Circle. The data from the International GNSS Service stations near the Arctic Circle were used to verify the ionospheric total electron contents derived from the kinematic data. The results suggested that the global ionospheric model had an approximate regional accuracy of 12 total electron content units (TECu) within the Arctic Circle and deviated from the actual ionospheric total electron content value by about 4 TECu.

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A Refinement Method of Real-Time Ionospheric Model for China

Remote Sensing ◽

10.3390/rs12203354 ◽

2020 ◽

Vol 12 (20) ◽

pp. 3354

Author(s):

Yang Wang ◽

Yibin Yao ◽

Liang Zhang ◽

Mingshan Fang

Keyword(s):

Real Time ◽

Total Electron Content ◽

Global Navigation Satellite Systems ◽

Single Frequency ◽

Electron Content ◽

Vertical Total Electron Content ◽

Ionospheric Model ◽

Total Electron ◽

Satellite Systems ◽

Refinement Method

Ionospheric delay is a crucial error source and determines the source of single-frequency precise point positioning (SF-PPP) accuracy. To meet the demands of real-time SF-PPP (RT-SF-PPP), several international global navigation satellite systems (GNSS) service (IGS) analysis centers provide real-time global ionospheric vertical total electron content (VTEC) products. However, the accuracy distribution of VTEC products is nonuniform. Proposing a refinement method is a convenient means to obtain a more accuracy and consistent VTEC product. In this study, we proposed a refinement method of a real-time ionospheric VTEC model for China and carried out experiments to validate the model effectiveness. First, based on the refinement method and the Centre National d’Études Spatiales (CNES) VTEC products, three refined real-time global ionospheric models (RRTGIMs) with one, three, and six stations in China were built via GNSS observations. Second, the slant total electron content (STEC) and Jason-3 VTEC were used as references to evaluate VTEC accuracy. Third, RT-SF-PPP was used to evaluate the accuracy in the positioning domain. Results showed that even if using only one station to refine the global ionospheric model, the refined model achieved a better performance than CNES and the Center for Orbit Determination in Europe (CODE). The refinement model with six stations was found to be the best of the three refinement models.

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Estimation of Total Electron Content and Instrumental Biases of Low Latitude Global Positioning System Stations Using Kalman Filter

IETE Journal of Research ◽

10.4103/0377-2063.72772 ◽

2010 ◽

Vol 56 (5) ◽

pp. 235 ◽

Cited By ~ 6

Author(s):

Dhiraj Sunehra ◽

K Satyanarayana ◽

CS Viswanadh ◽

AD Sarma

Keyword(s):

Kalman Filter ◽

Total Electron Content ◽

Global Positioning System ◽

Electron Content ◽

Positioning System ◽

Low Latitude ◽

Total Electron ◽

Global Positioning

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Kalman filter estimation of plasmaspheric total electron content using GPS

Radio Science ◽

10.1029/2008rs004070 ◽

2009 ◽

Vol 44 (1) ◽

pp. n/a-n/a ◽

Cited By ~ 19

Author(s):

Charles S. Carrano ◽

Adela Anghel ◽

Richard A. Quinn ◽

Keith M. Groves

Keyword(s):

Kalman Filter ◽

Total Electron Content ◽

Electron Content ◽

Total Electron

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A sequential calibration technique to improve IRI using TEC estimates of the GNSS network in Europe

10.5194/egusphere-egu21-4190 ◽

2021 ◽

Author(s):

Ehsan Forootan ◽

Mona Kosary ◽

Saeed Farzaneh ◽

Maike Schumacher

Keyword(s):

Kalman Filter ◽

Total Electron Content ◽

Ensemble Kalman Filter ◽

Satellite System ◽

Electron Content ◽

Dual Frequency ◽

Iri Model ◽

Total Electron ◽

Wide Range ◽

Point Positioning

The development of space-geodetic observation techniques has brought out a wide range of applications such as positioning and navigation, where the Global Navigation Satellite System (GNSS) is the main tools to provide surveying measurements in these applications. Though GNSS signals enable the calculation of receiver's position, some errors restrict their accuracy. Among these errors, the ionospheric delay is considered as an important error source in the Standard Point Positioning (SPP) applications. Empirical ionospheric models such as Klobuchar, International Reference Ionosphere (IRI), and NeQuick are often applied for computing the Total Electron Content (TEC) within ionosphere and its equivalent delays. However the simulation and forecasting skills of these models are limited due to the simplified model structures and model sensitivity to the calibration period. In this study, we present a novel sequential Calibration approach based on the Ensemble Kalman Filter (C-EnKF) to improve the performance of TEC estimations for SPP applications. To demonstrate the results, the IRI model is used as our basis and the TEC estimates from 56 IGS stations in Europe are applied as observation. The C-EnKF is applied to calibrate some selected model parameter so that IRI can be tuned over Europe. The numerical assessments are performed against the TEC estimates from dual frequency GNSS measurements and against the final IONEX products (that are available with 11 days delays). Based on the forecasting results (during September 2017), we show that the accuracy of TEC estimates from the C-EnKF is improved in the range of 3.7-64.87% compared to IRI.&#160;Keywords: Ionosphere, Sequential Calibration, Ensemble Kalman Filter (EnKF), IRI, Total Electron Content (TEC), Standard Point Positioning (SPP), GNSS

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ANALYSIS OF IONOSPHERIC TEC ANOMALIES DURING SUPER TYPHOONS MEGI AND MERANTI

Meteorologiya i Gidrologiya ◽

10.52002/0130-2906-2021-3-117-126 ◽

2021 ◽

Vol 3 ◽

pp. 117-126

Author(s):

J. SUN ◽

◽

Z. ZHANG ◽

X. LIU ◽

C. ZHANG ◽

...

Keyword(s):

Total Electron Content ◽

Orbit Determination ◽

Electron Content ◽

Ionospheric Model ◽

Grid Data ◽

Total Electron ◽

Super Typhoon ◽

Ionospheric Total Electron Content ◽

Typhoon Center ◽

Typhoon Event

In this paper, we detected and analyzed ionospheric anomalies during the 2016 super typhoons Megi and Meranti using the sliding interquartile range method applied to the ionospheric total electron content (TEC) grid data from the Global Ionospheric Model (GIM) provided by the Center for Orbit Determination in Europe (CODE). We found that ionospheric TEC anomalies occurred 2 days before the origination of super typhoon Megi. The anomalies occurred from 02:00 to 12:00 local time over a period of 10 h, with a maximum outlier of 12 TEC units over the typhoon center. Anomalies occurred in the ionosphere over both the area near the typhoon center and the corresponding equatorial magnetic conjugate region. The anomalies in both areas showed approximately the same trends. It is very likely that the disturbances from the ionospheric anomalies over the typhoon center were one of the precursors for the typhoon event. Similar ionospheric anomalies also occurred in the ionosphere 2 days before the formation and development of super typhoon Meranti...

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