Аннотация:We present the results of ionospheric imaging by the radio tomographic (RT) methods based on the Navigation Satellite Systems (GNSS). GNSS include the first-generation low orbiting (LO) systems (Tsikada, Transit, etc.) and second-generation high orbiting (HO) systems (GPS and GLONASS, which have been put in operation, and Galileo, BeiDou, and QZSS systems, which are currently under development in Europe, China, and Japan). The GNSS constellations and the networks of ground receivers are suitable for probing the ionosphere along different rays and processing the obtained data by tomographic inversion procedures.
The results discussed in this work are obtained by the methods of low orbiting and high orbiting radio tomography (LORT and HORT, respectively). We present the examples of tomographic images of the subequatorial, midlatitude, subauroral, and auroral ionosphere in different regions of the world. The RT images of the Arctic ionosphere demonstrate different structures (characteristic circumpolar ring structures, ionization patches, tongues of ionization (TOIs), etc.)
The GNSS RT methods are suitable for imaging the ionospheric disturbances caused
by the tsunami wave propagation. We analyze the ionospheric disturbances after the strongest Tohoku earthquake in Japan (March 11, 2011). The RT reconstructions are compared to the measurements by the ionosondes and Global Ionospheric Maps (GIM).