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RADIO SCIENCE, VOL. 43, RS3001, doi:10.1029/2007RS003716, 2008

Three-dimensional tomography of ionospheric variability using a dense GPS receiver array

Jeffrey K. Lee

Department of Electrical and Computer Engineering and the Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA


Farzad Kamalabadi

Department of Electrical and Computer Engineering and the Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA


Jonathan J. Makela

Department of Electrical and Computer Engineering and the Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA


Abstract

This paper investigates the localized 3D imaging of equatorial ionospheric depletions and mesoscale traveling ionospheric disturbances (MS-TIDs) with a dense ground-based GPS receiver array. A tomographic forward model is presented using dual-frequency GPS measurements from receivers in the Japanese GPS Earth Observation Network (GEONET). The application of inversion techniques to the discrete observation matrix allows a 3D electron density volume to be reconstructed from the GPS total electron content (TEC) measurements. Because the inverse problem is ill-posed and ill-conditioned, regularization functionals are used to constrain the solution in the presence of noise. To capture the abrupt height and density variations of the structures, a technique using nonconvex penalty constraints is proposed. The reconstructions have 40 to 50-km horizontal and 30-km vertical resolution. Time series of reconstructed images show the evolution and movement of ionospheric structures through the reconstruction region. The results are analyzed and compared with independent ionosonde measurements and vertical TEC (VTEC) maps constructed from the observed GPS data.

Received 26 June 2007; accepted 26 February 2008; published 6 May 2008.

Keywords: ionospheric tomography; GPS; inverse problem.

Index Terms: 6982 Radio Science: Tomography and imaging (7270, 8180); 3260 Mathematical Geophysics: Inverse theory; 2435 Ionosphere: Ionospheric disturbances; 2443 Ionosphere: Midlatitude ionosphere; 6974 Radio Science: Signal processing (0674).

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Citation: Lee, J. K., F. Kamalabadi, and J. J. Makela (2008), Three-dimensional tomography of ionospheric variability using a dense GPS receiver array, Radio Sci., 43, RS3001, doi:10.1029/2007RS003716.