Tomographic reconstruction of the ionospheric electron density as a function of space and time

• Published in: Advances in space research Vol. 43; no. 11; pp. 1702 - 1710
• Main Authors: Erturk, Onur, Arikan, Orhan, Arikan, Feza
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 02-06-2009; Elsevier
• Subjects: Astronomy; Computerized Ionospheric Tomography (CIT); Earth, ocean, space; Exact sciences and technology; External geophysics; Ground Positioning Satellites (GPS); Ionosphere; Ionospheric reconstruction; Occultation data; Singular Value Decomposition (SVD); Voxelization; Occultation data; Singular Value Decomposition (SVD); Computerized Ionospheric Tomography (CIT); Voxelization; Ionospheric reconstruction; Ionosphere; Ground Positioning Satellites (GPS); Function space; Singular value; Variability; Electron distribution; Total electron content; Density distribution; Space research; Computerized tomography; Global Positioning System; Occultations; Space-time; Models; Ill posed problem; Electron density; Regularization; Singular value decomposition; Strength functions
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/j.asr.2008.08.018

Electron density distribution is the major determining parameter of the ionosphere. Computerized Ionospheric Tomography (CIT) is a method to reconstruct ionospheric electron density image by computing Total Electron Content (TEC) values from the recorded Global Positioning Satellite System (GPS) signals. Due to the multi-scale variability of the ionosphere and inherent biases and errors in the computation of TEC, CIT constitutes an underdetermined ill-posed inverse problem. In this study, a novel Singular Value Decomposition (SVD) based CIT reconstruction technique is proposed for the imaging of electron density in both space (latitude, longitude, altitude) and time. The underlying model is obtained from International Reference Ionosphere (IRI) and the necessary measurements are obtained from earth based and satellite based GPS recordings. Based on the IRI-2007 model, a basis is formed by SVD for the required location and the time of interest. Selecting the first few basis vectors corresponding to the most significant singular values, the 3-D CIT is formulated as a weighted least squares estimation problem of the basis coefficients. By providing significant regularization to the tomographic inversion problem with limited projections, the proposed technique provides robust and reliable 3-D reconstructions of ionospheric electron density.