scholarly journals Data Assimilation of Ground‐Based GPS and Radio Occultation Total Electron Content for Global Ionospheric Specification

2017 ◽  
Vol 122 (10) ◽  
pp. 10,876-10,886 ◽  
Author(s):  
C. Y. Lin ◽  
T. Matsuo ◽  
J. Y. Liu ◽  
C. H. Lin ◽  
J. D. Huba ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Total Electron Content ◽  
Radio Occultation ◽  
Electron Content ◽  
Total Electron

Improving Total Electron Content (TEC) Models for Geodetic Applications

2020 ◽  
Author(s):  
Mona Kosary ◽  
Saeed Farzaneh ◽  
Maike Schumacher ◽  
Ehsan Forootan
Keyword(s):  
Data Assimilation ◽  
Total Electron Content ◽  
Precise Point Positioning ◽  
Main Tool ◽  
Model Parameters ◽  
Electron Content ◽  
Total Electron ◽  
Radio Science ◽  
Imperfect Knowledge ◽  
Point Positioning

<p>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’s characteristics such as selected important CCIR (Comité Consultatif International des Radiocommunicationsand) URSI (International Union of Radio Science) coefficients.  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’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.</p><p><strong>Keywords: </strong>Ionosphere, Calibration and Data Assimilation (C/DA), IRI, Total Electron Content (TEC), Precise Point Positioning (PPP), GNSS</p>

scholarly journals Modeling Total Electron Content derived from radio occultation measurements by COSMIC satellites over the African Region

2019 ◽  
Author(s):  
Patrick Mungufeni ◽  
Claudia Stolle ◽  
Sripathi Samireddipalle ◽  
Yenca Migoya-Orué ◽  
Yong Ha Kim
Keyword(s):  
Total Electron Content ◽  
Local Time ◽  
Radio Occultation ◽  
Mean Squared Error ◽  
Electron Content ◽  
Quiet Time ◽  
African Region ◽  
Total Electron ◽  
Flux Level ◽  
Binned Data

Abstract. This study developed a model of Total Electron Content (TEC) over the African region. The TEC data were derived from radio occultation measurements done by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. Geomagnetically quiet time (Kp  −20 nT) data during the years 2008–2011, and 2013–2017 were binned according to local time, seasons, solar flux level, geographic longitude, and dip latitude. Cubic B splines were fitted to the binned data to obtain the model. The model was validated using TEC data of the years 2012 and 2018. The validation exercise revealed that, approximation of observed TEC data by our model produces root mean squared error of 4.8 TECU. Moreover, the modeled TEC data correlated highly with the observed TEC data (r = 0.93). Our model is the first attempt to predict TECs over the entire African region by using extensive COSMIC TEC measurements. Due to the extensive input data and the good modeling technique, we were able to reproduce the well-known features such as local time, seasonal, solar activity, and spatial variations of TEC over the African region.

scholarly journals US-TEC: A new data assimilation product from the Space Environment Center characterizing the ionospheric total electron content using real-time GPS data

Radio Science ◽  
2006 ◽  
Vol 41 (6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Tim Fuller-Rowell ◽  
Eduardo Araujo-Pradere ◽  
Cliff Minter ◽  
Mihail Codrescu ◽  
Paul Spencer ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Real Time ◽  
Total Electron Content ◽  
Space Environment ◽  
Gps Data ◽  
Electron Content ◽  
Total Electron ◽  
Ionospheric Total Electron Content

scholarly journals Modeling total electron content derived from radio occultation measurements by COSMIC satellites over the African region

2020 ◽  
Vol 38 (6) ◽  
pp. 1203-1215
Author(s):  
Patrick Mungufeni ◽  
Sripathi Samireddipalle ◽  
Yenca Migoya-Orué ◽  
Yong Ha Kim
Keyword(s):  
Root Mean Square Error ◽  
Mean Square Error ◽  
Root Mean Square ◽  
Total Electron Content ◽  
Local Time ◽  
Radio Occultation ◽  
Electron Content ◽  
Mean Square ◽  
African Region ◽  
Total Electron

Abstract. This study developed a model of total electron content (TEC) over the African region. The TEC data were obtained from radio occultation measurements done by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. Data during geomagnetically quiet time (Kp < 3 and Dst > −20 nT) for the years 2008–2011 and 2013–2017 were binned according to local time, seasons, solar flux level, and geographic longitude and latitude. B splines were fitted to the binned data to obtain model coefficients. The model was validated using actual COSMIC TEC data of the years 2012 and 2018. The validation exercise revealed that approximation of observed TEC data by our model produces a root mean square error of 5.02 TECU (total electron content unit). Moreover, the modeled TEC data correlated highly with the observed TEC data (r=0.93). Due to the extensive input data and the applied modeling technique, we were able to reproduce well-known TEC features such as local time, seasonal, solar activity cycle, and spatial variations over the African region. Further validation of our model using TEC measured by ionosonde stations over South Africa at Hermanus, Grahamstown, and Louisville revealed r values > 0.92 and root mean square error (RMSE) < 5.56 TECU. These validation results imply that our model can estimate TEC fairly well that would be measured by ionosondes over locations which do not have the instrument. Another element of the significance of this study is the fact that it has shown the potential of using basis spline functions for modeling ionospheric parameters such as TEC over the entire African region.

scholarly journals Determination of Total Electron Content at Equatorial Region—Thailand Using Radio Occultation Technique

2016 ◽  
Vol 06 (02) ◽  
pp. 319-328 ◽  
Author(s):  
Wasiu Akande Ahmed ◽  
Ganiyu Ishola Agbaje ◽  
Sikiru Yommy Aiyeola ◽  
Bola O. Balogun ◽  
Ngbede Joshua Ada Echoda ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Radio Occultation ◽  
Equatorial Region ◽  
Electron Content ◽  
Total Electron
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