Estimation of ionospheric threat model parameters for GBAS using gnss data for Marmara Region

Date

2016

Author

Yeganehsahab, Amir

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To establish a proper Ground-Based Augmentation System (GBAS), the estimation of ionospheric threat model parameters is of paramount importance. For this, it is also necessary to make use of precise ionospheric models in terms of local or regional coverages in order to generate Vertical Total Electron Content (VTEC). VTEC can be calculated from a local ionospheric model on the basis of a second order surface polynomial using GNSS data. Therefore, a Variance Component Estimation technique has been performed to weight different kind of observations from Global Positioning System (GPS) and GLObal NAvigation Satellite System (GLONASS). The VTEC parameters are estimated together with Differential Code Bias (DCB) parameters to get calibrated VTECs which in turn are needed for the estimation of correct ionospheric gradients. To validate the results visually and automatically, estimated VTEC values have been compared with that of Global Ionosphere Models (GIMs) provided by International GPS Service (IGS). The calculation of spatial ionospheric gradients is based on two different approaches, namely the Rate of Change and Station-Pair gradients which are referred to different geometrical concepts. The resulting gradients have been used to estimate the Ionospheric Threat Model Parameters for Ground Based Augmentation System (GBAS). From the estimation of Threat Model parameters can be concluded that both approaches provide consistent results. For the Marmara region, no significant high ionospheric gradient has been detected applying both approaches to GNSS data during geomagnetic storms between 2010- 2015. Consequently, estimated threat model parameters do not show considerable differences in this region.

Subject Keywords

Ionosphere., Ionospheric electron density., Global Positioning System., Geographic information systems.

URI

http://etd.lib.metu.edu.tr/upload/12620556/index.pdf
https://hdl.handle.net/11511/25925

Collections

Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

A. Yeganehsahab, “Estimation of ionospheric threat model parameters for GBAS using gnss data for Marmara Region,” M.S. - Master of Science, Middle East Technical University, 2016.