Nighttime medium‐scale traveling ionospheric disturbances detected by network GPS receivers in Taiwan

The nighttime medium‐scale traveling ionospheric disturbances (MSTIDs) are detected by the network GPS receivers in Taiwan for the first time. The two‐dimensional mapping technique (a spatial resolution of 0.05° × 0.05° in latitude and longitude with 5 × 5 pixels smoothing) is applied on the data of TEC perturbations (TECp) and GPS phase fluctuations (ΔTEC/min). The results show that the MSTIDs move southwestward to latitude of 20.5°N with a horizontal velocity between 100 and 160 m/s and a wavelength of about 500 km. The wavefronts of the MSTIDs are aligned along the northwest‐southeast direction. Furthermore, the greater ∣ΔTEC/min∣ values are corresponding to the wave peak and trough of TECp. This coincidence indicates that the MSTIDs play an important role for the generation of F region irregularities in the low‐latitude ionosphere.