B-spline modeling of VTEC over Turkey using GPS observations

2010-05-01
Nohutcu, M.
Karslıoğlu, Mahmut Onur
Schmidt, M.
In this study we propose two approaches to model the Vertical Total Electron Content (VTEC) of the ionosphere with quadratic B-spline functions. For the 2-D case, VTEC is modeled in a Sun-fixed reference frame. In the 3-D approach, the 2-D model is extended to represent the temporal variations in an Earth-fixed reference frame. The localizing features of B-splines allow resolving finer structures for the regions with a sufficient number of observations by increasing the level of functions. To reduce the effects of outliers, Iteratively Re-weighted Least Squares (IRIS) with a bi-square weighting function as a robust regression algorithm is applied for parameter estimation. Another iterative method LSQR is performed for the solution of the linear systems providing a regularization effect for ill-conditioned problems. B-spline approaches are applied to real data obtained from the ground-based GPS observations over Turkey. Results are compared with the solutions of the Bernese GPS Software.

Citation Formats
M. Nohutcu, M. O. Karslıoğlu, and M. Schmidt, “B-spline modeling of VTEC over Turkey using GPS observations,” JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS, vol. 72, pp. 617–624, 2010, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/51176.