This paper presents a statistical result of large‐scale traveling ionospheric disturbances (LSTIDs) associated with moving solar terminator in China during 12 months from February 2011 to January 2012. The LSTIDs are identified by the two‐dimensional total electron content (TEC) perturbation maps, which are built based on the observations of GPS network data from China. The GPS observations are combined with the observations from an ionosonde chain established by the Institute of Geology and Geophysics, Chinese Academy of Sciences. A total of 135 LSTID events are identified at dawn, while there is indiscernible LSTID at dusk. Meanwhile, these LSTIDs are captured by the ionosonde chain which shows that there are perturbations in the virtual heights during the passage of LSTIDs at the height between 200 and 700 km. The occurrence rate of LSTIDs shows a maximum in winter and a minimum in summer. The LSTIDs propagate across China with phase front widths larger than 1500 km. The propagation direction of LSTIDs is northwestward in winter, southwestward in summer, and quasi‐westward in equinoxes, respectively. The average period, horizontal phase velocity, and horizontal wavelength of LSTIDs are 79 ± 12 min, 288 ± 43 m/s, and 1503 ± 205 km, respectively. The relative TEC perturbations of the LSTIDs attenuate as the LSTIDs travel across China.
[1] This paper reports the first results of the 2D imaging of large-scale traveling ionospheric disturbances (LSTID) using GPS network data from China, combined with observations of these events using an ionosonde chain. 2D TEC perturbation maps for North America were also constructed to allow the study of LSTIDs on a global scale. During the medium storm on 28 May 2011, the onset of a substorm initiated a slow-speed LSTID over North America just after midnight. Subsequently, an LSTID reached China 1.5 hours later, at dusk. A second LSTID was observed over China before midnight, 6.6 hours after substorm onset. The phase fronts of the China events had a front width of at least 1600 km, and moved southwestwards at a speed of 540 AE 85 m/s and 362 AE 89 m/s, respectively. Ionosonde data addressed a downward vertical phase velocity of $75 m/s for the dusk event and $60 m/s for the night event. Although the nighttime LSTID travelled farther south than the earlier dusk event, both disappeared in South China, and this was due to increase of the attenuation at low latitudes. According to the energy dissipation equation of atmospheric gravity waves there is severe dissipation due to viscosity and heat conductivity at low latitudes, since such dissipation increases strongly with time; dissipation due to ion drag is less important but cannot be ignored because of enhancement in background TEC; In addition, uplift of the ionosphere at low latitudes is another factor that results in a reduced amplitude of TEC perturbation at low latitudes.
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