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Article

Adaptive Modeling of the Global Ionosphere Vertical Total Electron Content

1
Deutsches Geodätisches Forschungsinstitut der Technischen Universität München (DGFI-TUM), Arcisstraße 21, 80333 München, Germany
2
Bundeswehr Geoinformation Center (BGIC), 53879 Euskirchen, Germany
*
Author to whom correspondence should be addressed.
Remote Sens. 2020, 12(11), 1822; https://doi.org/10.3390/rs12111822
Received: 21 April 2020 / Revised: 21 May 2020 / Accepted: 1 June 2020 / Published: 4 June 2020
The Kalman filter (KF) is widely applied in (ultra) rapid and (near) real-time ionosphere modeling to meet the demand on ionosphere products required in many applications extending from navigation and positioning to monitoring space weather events and naturals disasters. The requirement of a prior definition of the stochastic models attached to the measurements and the dynamic models of the KF is a drawback associated with its standard implementation since model uncertainties can exhibit temporal variations or the time span of a given test data set would not be large enough. Adaptive methods can mitigate these problems by tuning the stochastic model parameters during the filter run-time. Accordingly, one of the primary objectives of our study is to apply an adaptive KF based on variance component estimation to compute the global Vertical Total Electron Content (VTEC) of the ionosphere by assimilating different ionospheric GNSS measurements. Secondly, the derived VTEC representation is based on a series expansion in terms of compactly supported B-spline functions. We highlight the morphological similarity of the spatial distributions and the magnitudes between VTEC values and the corresponding estimated B-spline coefficients. This similarity allows for deducing physical interpretations from the coefficients. In this context, an empirical adaptive model to account for the dynamic model uncertainties, representing the temporal variations of VTEC errors, is developed in this work according to the structure of B-spline coefficients. For the validation, the differential slant total electron content (dSTEC) analysis and a comparison with Jason-2/3 altimetry data are performed. Assessments show that the quality of the VTEC products derived by the presented algorithm is in good agreement, or even more accurate, with the products provided by IGS ionosphere analysis centers within the selected periods in 2015 and 2017. Furthermore, we show that the presented approach can be applied to different ionosphere conditions ranging from very high to low solar activity without concerning time-variable model uncertainties, including measurement error and process noise of the KF because the associated covariance matrices are computed in a self-adaptive manner during run-time. View Full-Text
Keywords: ionosphere modeling; adaptive Kalman filter; variance component estimation; B-splines; VTEC ionosphere modeling; adaptive Kalman filter; variance component estimation; B-splines; VTEC
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MDPI and ACS Style

Erdogan, E.; Schmidt, M.; Goss, A.; Görres, B.; Seitz, F. Adaptive Modeling of the Global Ionosphere Vertical Total Electron Content. Remote Sens. 2020, 12, 1822. https://doi.org/10.3390/rs12111822

AMA Style

Erdogan E, Schmidt M, Goss A, Görres B, Seitz F. Adaptive Modeling of the Global Ionosphere Vertical Total Electron Content. Remote Sensing. 2020; 12(11):1822. https://doi.org/10.3390/rs12111822

Chicago/Turabian Style

Erdogan, Eren, Michael Schmidt, Andreas Goss, Barbara Görres, and Florian Seitz. 2020. "Adaptive Modeling of the Global Ionosphere Vertical Total Electron Content" Remote Sensing 12, no. 11: 1822. https://doi.org/10.3390/rs12111822

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