The Initial Results from the LITN of the FORMOSAT-3 TBB Program


Beginning in 2006, four ground stations located at Chung-Li (25.136°N, 121.539°E), TasoTun (23.981°N, 120.697°E), CheCheng (22.725°N, 120.544°E), and tropical Itu Aba Island (10.06°N, 114.350°E) were set up to receive beacon signals from six FORMOSAT-3/COSMIC (Bernhardt et al. 2000) and other NNSS-like satellites. By applying differential Doppler technique on three quadrature components of the three-band beacon signals, we were able to obtain total electric contents (TEC) values and scintillation along the radio path through the ionosphere. Such measurements can be used to derive regional ionospheric irregularity and tomography. In this paper, we have confirmed the power patterns contributed from the transmitting antennas on board FS3/COSMIC and the ground-based receiving antennas. The multiplicative algebraic reconstruction technique (MART) algorithm has also been implemented to reconstruct ionospheric tomography images. Observations of the diurnal variations and the dynamics of equatorial anomaly showed that the equatorial anomaly appeared at 0800 LT, and then subsequently moved toward the Earth's poles. The north crest was strongest at ~1300 LT and its core was located at about 10°N of the magnetic latitude (~20°N geographic latitude). Afterwards, the crest moved toward the equator after sunset and disappeared after midnight.

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