Ionospheric disturbances in the East-Asian region during geomagnetic storm in November, 2004 Original Research Article

Results of the study into variations of the ionospheric parameters during the intense geomagnetic storm on November 7–11, 2004 in the 20–80°N, 80–160°E sectors are presented. These used data from ionospheric stations and total electron content (TEC) measurements obtained from the network of the GPS ground-based receivers and the receiver onboard the CHAMP satellite. Periods of total absorption and blanketing sporadic E layers were observed at high latitudes, whereas long-lasting negative disturbances which are typical of geomagnetic storms of high intensity were detected at midlatitudes. In the afternoon hours of local time on November 8, 2004, a large-scale ionospheric disturbance was detected on the basis of foF2 and TEC measurements. The disturbance was propagating southwestward at a mean velocity of about 200 m/s. Comparison of the relative amplitude of this large-scale disturbance according to the total electron content (∼70%) and foF2 (∼80%) measurements made it possible to assume that the disturbance was extended in height. A similar disturbance of smaller intensity was observed on November 10.