Development and analysis of 3D ionosphere modeling using base functions and GPS data over Iran

Abstract

In this study, a 3D-model of the electron density has been performed using the global positing system (GPS) measurements over Iran. 2D spherical harmonic functions and empirical orthogonal functions are used as base functions to model the horizontal and the vertical content of the electron density, respectively. The ionosonde data in Tehran (u = 35.7382°, k = 51.3851°) has been used for choosing an optimum value for the regularization parameter. To apply the method for constructing a 3D-image of the electron density, GPS measurements of the Iranian permanent GPS network (at 3-day in 2007) have been used. The instability of solution has been numerically analyzed and the Tikhonov method has been used for regularizing the solution. To come up with an optimum regularization parameter, the relative error in electron density profile computed from ionosonde measurements and their 3D model are minimized. The modeling region is between 24°to 40°N and 44°to 64°W. The result of 3D-Model has been compared to that of the international reference ionosphere model 2012 (IRI-2012). The data analysis shows that the latitudinal section of ionosphere electron density from 3D technique supports the expected time and height variations in ionosphere electron density. Moreover, these findings show that the height of maximum electron density is changed during the day and night and confirms the efficiency of multi-layer models in comparison to single-layer models. This method could recover 64-99 % of the ionosphere electron density.

GNSS Vulnerabilities and Existing Solutions: A Review of the Literature

“…A number of methods have been proposed in the literature to compensate for the delays caused by the ionosphere layer. Some of these include computerized ionospheric tomography (CIT), iterative algorithms, non-iterative algorithms and data assimilation techniques [64]- [67].…”