Large-scale traveling ionospheric disturbances observed by GPS total electron content during the magnetic storm of 29-30 October 2003

Abstract

We have investigated the propagation of large-scale traveling ionospheric disturbances (LSTIDs) during the super magnetic storm of 29-30 October 2003. Two-dimensional total electron content (TEC) perturbation maps over North America were built using TEC data provided by the American GPS network and the International GNSS Service. Three LSTID events were observed in the range of 30°N-50°N, 60°W-110°W during this period. The first two LSTIDs occurred consecutively during 0620-0800 UT on 29 October at the local time of midnight, right after the onset of the big substorm; the third one was found at noon during the expansion phase of another substorm on 30 October. The phase fronts of these LSTIDs passed over the United States and traveled southwestward to the distance of ∼2000 km with the maximum front width of ∼4000 km and the duration of less than 2 hours. The maximum amplitude of TEC perturbations attained 3 total electron content units (TECUs). The results differ from the former observation of Afraimovich and Voeykov (2004) and Afraimovich et al. (2006), who reported a solitary LSTID propagating southwestward over the United States with the amplitudes of up to 14 TECU on 30 October 2003. We have checked the magnetic H component observed at the geomagnetic observatories in North America and found it is most likely that the auroral westward electrojet was the cause of the LSTIDs on 29 October. The source region for these TIDs was likely to be located several hundred kilometers north of 50°N. Cross-spectral analysis was conducted to obtain the global propagation characteristics of LSTIDs during this superstorm. Equatorward LSTIDs were found in all the three sectors of North America, Europe, and Asia, showing high correlation with the occurrence of auroral substorms. Copyright 2007 by the American Geophysical Union.