Near real-time estimation of ionosphere vertical total electron content from GNSS satellites using B-splines in a Kalman filter

Erdogan, Eren
Schmidt, Michael
Seitz, Florian
Durmaz, Murat
Abstract. Although the number of terrestrial global navigation satellite system (GNSS) receivers supported by the International GNSS Service (IGS) is rapidly growing, the worldwide rather inhomogeneously distributed observation sites do not allow the generation of high-resolution global ionosphere products. Conversely, with the regionally enormous increase in highly precise GNSS data, the demands on (near) real-time ionosphere products, necessary in many applications such as navigation, are growing very fast. Consequently, many analysis centers accepted the responsibility of generating such products. In this regard, the primary objective of our work is to develop a near real-time processing framework for the estimation of the vertical total electron content (VTEC) of the ionosphere using proper models that are capable of a global representation adapted to the real data distribution. The global VTEC representation developed in this work is based on a series expansion in terms of compactly supported B-spline functions, which allow for an appropriate handling of the heterogeneous data distribution, including data gaps. The corresponding series coefficients and additional parameters such as differential code biases of the GNSS satellites and receivers constitute the set of unknown parameters. The Kalman filter (KF), as a popular recursive estimator, allows processing of the data immediately after acquisition and paves the way of sequential (near) real-time estimation of the unknown parameters. To exploit the advantages of the chosen data representation and the estimation procedure, the B-spline model is incorporated into the KF under the consideration of necessary constraints. Based on a preprocessing strategy, the developed approach utilizes hourly batches of GPS and GLONASS observations provided by the IGS data centers with a latency of 1 h in its current realization. Two methods for validation of the results are performed, namely the self consistency analysis and a comparison with Jason-2 altimetry data. The highly promising validation results allow the conclusion that under the investigated conditions our derived near real-time product is of the same accuracy level as the so-called final post-processed products provided by the IGS with a latency of several days or even weeks.
Annales Geophysicae


Effects of microwave and ultrasonic extraction methods on total phenolic content of nettle (Urtica diocia)
Ince, Alev Emine; Şahin, Serpil; Sumnu, Gulum (null; 2011-12-01)
Abstract. Effects of different extraction methods at different conditions on total phenolic content (TPC) of nettle (Urtica diocia) were investigated. Water was used as solvent. TPC analysis was performed according to Folin-Ciocalteu method. In microwave extraction, heating was achieved using microwaves at 407W power level. Effects was obtained as 1:30 solid-to-solvent ratio for 10min. Extraction was also performed conventionally at 1:30 solid-to-solvent ratio for 30min for comparison. There was no signific...
Circulation of the Turkish Straits System under interannual atmospheric forcing
Aydoğdu, Ali; Pinardi, Nadia; Özsoy, Emin; Danabasoglu, Gokhan; Gürses, Özgür; Karspeck, Alicia (Copernicus GmbH, 2018-9-11)
Abstract. A simulation of the Turkish Straits System (TSS) using a high-resolution, three-dimensional, unstructured mesh ocean circulation model with realistic atmospheric forcing for the 2008–2013 period is presented. The depth of the pycnocline between the upper and lower layers remains stationary after 6 years of integration, indicating that despite the limitations of the modelling system, the simulation maintains its realism. The solutions capture important responses to high-frequency atmospheric...
Reviewing the Implementation of Life Sciences Curriculum in Turkey Using Elicitation Techniques
Engin Demir, Cennet (2018-06-01)
Abstract. The aims of this case study were (1) to investigate the general characteristics of the Life Sciences Curriculum (LSC); (2) to examine how the LSC is implemented in a public primary school from the perspectives of teachers, students and administrators; and (3) to identify whether implementation of the curriculum was in line with the principles of constructivist pedagogy. The study participants consisted of the school administrator, 2 co-administrators, 4 classroom teachers and 87 students fr...
Postglitch relaxation of the crab pulsar after its first four major glitches: The combined effects of crust cracking, formation of vortex depletion region and vortex creep
Alpar, MA; Chau, HF; Cheng, KS; Pines, D (American Astronomical Society, 1996-03-10)
Following the application of vortex creep theory (Alpar et al. 1984; Alpar et al. 1993; Chau et al. 1993) to the postglitch behavior of the Vela pulsar, we extend the model to cover the postglitch behavior of the Crab pulsar (Alpar et al. 1994). We propose that the comparatively modest (Delta Omega/Omega similar to 10(-8)) and somewhat infrequent (similar to 6 yr interglitch intervals) Crab pulsar glitches are caused by crust cracking during starquakes induced by pulsar spin-down (Ruderman 1976; Baym & Pine...
BAYIN, SS (Springer Science and Business Media LLC, 1992-01-01)
We point out that the conclusions of a recent Letter by Yavuz et al. are based on a misunderstanding of basic perturbation theory.
Citation Formats
E. Erdogan, M. Schmidt, F. Seitz, and M. Durmaz, “Near real-time estimation of ionosphere vertical total electron content from GNSS satellites using B-splines in a Kalman filter,” Annales Geophysicae, pp. 263–277, 2017, Accessed: 00, 2020. [Online]. Available: