Study of the ionospheric TEC using GPS during the large solar flare burst on Nov. 6, 1997

Using the data from 15 global positioning system (GPS) stations scattered between 28° N—45° N and 90° W—77° E we obtained the total electron content (TEC) variations with time during a large solar flare. The results indicated that the flare makes the TEC of ionosphere increasing in a large spatial area. The amounts of the TEC enhancement are mainly determined by the local time of subionospheric point, and the largest TEC enhancement is about 2.5 TECU. It is also concluded that the TEC enhancement is not symmetrical about the local noon time, the TEC enhancement values during morning hours are larger than those of the afternoon hours.