Earth Planets Space, Vol. 60 (No. 7), pp. 727-735, 2008
Thomas Hobiger, Tetsuro Kondo, and Yasuhiro Koyama
Space-Time Standards Group, Kashima Space Research Center, National Institute of Information and Communications Technology, 893-1 Hirai, Kashima 314-0012, Japan
(Received September 3, 2007; Revised February 20, 2008; Accepted March 11, 2008; Online published August 4, 2008)
A simple and relatively fast method (C-SART) is presented for tomographic reconstruction of the electron density distribution in the ionosphere using smooth fields. Since it does not use matrix algebra, it can be implemented in a low-level programming language, which speeds up applications significantly. Compared with traditional simultaneous algebraic reconstruction, this method facilitates both estimation of instrumental offsets and consideration of physical principles (expressed in the form of finite differences). Testing using a 2D scenario and an artificial data set showed that C-SART can be used for radio tomographic reconstruction of the electron density distribution in the ionosphere using data collected by global navigation satellite system ground receivers and low Earth orbiting satellites. Its convergence speed is significantly higher than that of classical SART, but it needs to be speeded up by a factor of 100 or more to enable it to be used for (near) real-time 3D tomographic reconstruction of the ionosphere.
Key words: Ionosphere, TEC, tomography, GNSS, SART, differential code biases.