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Journal Electromagnetic Waves and Electronic Systems №8 for 2010 г.
Article in number:
Comparison of Global Ionospheric Maps and Satellite Low-Orbital Radio Tomography
Keywords: ionosphere total electron content ionospheric radio tomography global ionospheric maps Global Ultraviolet Imager (GUVI) data
Authors:
E.S. Andreeva, S.A. Kalashnikova, N.Ya. Romanova
Abstract:
Modern methods of ionospheric research based on using of the net of high orbital navigation systems (GPS/GLONASS) receivers allow composing global ionospheric maps (GIM) of vertical total electron content (VTEC). Different approaches used by International GNSS service (IGS) are based on general idea of estimation of electron density profile (N(h)-profile) parameters. The GIM provided by IGS in the IONEX format have 2.5 degree resolution in longitude and 5 degrees in latitude; time increment is 2 hours. Existing low orbital navigation systems (like Russian "Tsykada" and American "Transit") and ground-based chains of receivers enable to obtain 2D cross-sections (a few thousand kilometers as long) of ionospheric electron density distribution in a vertical plane containing the satellite path and the receiving chain for a 10-15 minutes interval. Horizontal resolution of LORT is 20-30 km and vertical resolution is 30-40 km. Comparison of GIM data and ionospheric LORT results for LORT-systems in Russia (Moscow-Svalbard) and in Alaska region at different geomagnetic activity are carried out. The data of Global Ultraviolet Imager (GUVI) are used as additional information about ionosphere as long as radiation is proportional, at a first approximation, to the integral of squared electron density along the line of sight. It is shown that spatial resolution of GIM is significantly worse than 2.5° in latitude particularly during of geomagnetic storms and perturbations. Quite often the structures with scales of 5° and greater in latitude are not revealed in GIM. At the same time the structures with scales of about 0.5° and even much smaller are revealed by LORT and clearly seen in Global Ultraviolet Imager (GUVI) data. For quiet periods higher GIM VTEC compared to LORT VTEC, which might be due to the plasmaspheric contribution, are still noteworthy.
Pages: 53-59
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