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

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.