A modified three-dimensional ionospheric tomography algorithm with side rays
- 194 Downloads
The three-dimensional ionospheric tomography (3DCIT) algorithm based on Global Navigation Satellite System (GNSS) observations have been developed into an effective tool for ionospheric monitoring in recent years. However, because the rays that come into or come out from the side of the inversion region cannot be used, the distribution of the rays in the edge and bottom part of the inversion region is scarce and the electron density cannot be effectively improved in the inversion process. We present a three-dimensional tomography algorithm with side rays (3DCIT-SR) applying the side rays to the inversion. The partial slant total electron content (STEC) of side rays in the inversion region is obtained based on the NeQuick2 model and GNSS-STEC. The simulation experiment results show that the algorithm can effectively improve the distribution of GNSS rays in the inversion region. Meanwhile, the iteration accuracy has also been significantly improved. After the same number of iterations, the iterative results of 3DCIT-SR are closer to the truth than 3DCIT, in particular, the inversion of the edge regions is improved noticeably. The GNSS data of the International GNSS Service (IGS) stations in Europe are used to perform real data experiments, and the inversion results show that the electron density profiles of 3DCIT-SR are closer to the ionosonde measurements. The accuracy improvement of 3DCIT-SR is up to 56.3% while the improvement is more obvious during the magnetic storm compared to the case of a calm ionospheric state .
KeywordsThree-dimensional ionospheric tomography GNSS Side rays Inversion
The authors would like to thank the International Global Navigation Satellite System Service (IGS) for the data used in this work. The authors also thank the Global Ionosphere Radio Observatory for the ionosonde data. The ionosonde (PQ052) data were downloaded from ftp://ftp.ngdc.noaa.gov/ionosonde/data/.
- Austen JR, Franke SJ, Liu CH, Yeh KC (1986) Application of computerized tomography techniques to ionospheric research. In: Proceedings of the international beacon satellite symposium on radio beacon contribution to the study of ionization and dynamics of the ionosphere and to corrections to geodesy and technical workshop, University of Oulu, Finland, pp 25–35. http://adsabs.harvard.edu/abs/1986ibs..symp...2A
- Chen CH, Saito A, Lin CH, Yamamoto M, Suzuki S, Seemala GK (2016) Medium-scale traveling ionospheric disturbances by three-dimensional ionospheric GPS tomography. Earth Planets Space 68(32):1–9Google Scholar
- Hansen AJ, Walter T, Enge P (1997) Ionospheric correction using tomography. In: Proc. ION GPS-97, Institute of Navigation, Kansas City, MO, USA, September 16–19, pp 249–260Google Scholar
- Macalalad FV, Jr JH, Apostol JV, Preston FW (1993) Experimental ionospheric tomography with ionosonde input and EISCAT verification. Ann Geophys Ger 11(11–12):1064–1074Google Scholar
- Markkanen M, Lehtinen M, Nygrén T, Pirttilä J, Henelius P, Vilenius E, Tereshchenko ED, Khudukon BZ (1995) Bayesian approach to satellite radiotomography with applications in the Scandinavian sector. ISME J 8(11):2280–2289Google Scholar
- Mitchell CN, Spencer PSJ (2003) A three-dimensional time-dependent algorithm for ionospheric imaging using GPS. Ann Geophys Italy 46(4):687–696Google Scholar
- Pryse SE, Kersley L, Rice DL, Russell CD, Walker IK (1993) Tomographic imaging of the ionospheric mid-latitude trough. Ann Geophys 11(3):144–149Google Scholar