Abstract
A detailed study of geomagnetic pulsations of Рс5 with a frequency of ~ 2.8 mHz was carried out using data from the two-dimensional IMAGE network and magnetic stations located on the territory of Russia. Pc5 events occurred in the afternoon sector against the background of a magnetic storm on 27.08.2014 after 5-day period with low magnetic activity. In two-time intervals – at the beginning of the storm and during the period of maximum magnetic activity, instantaneous two-dimensional distributions of the magnetic field components Рс5 on the Earth’s surface were plotted. It was found that the ionospheric sources of Рс5 (Hall current vortices) have an elliptical shape with a larger axis in the south-north direction. At the beginning of the magnetic storm, a single burst of Рс5 pulsations was detected, the source center of which was located at the geomagnetic latitude ~ 67.5° (L ~ 6.8 Re) and it moved westward with a speed of ~ 0.7 km/s. The estimated size of this ionospheric source is ~ 150 km in the west-east direction and ~ 330 km in the south-north direction. During the maximum period of the magnetic storm, the Рс5 pulsations are produced by two ionospheric sources following each other. These ionospheric sources have a more elongated elliptical shape with axis sizes in the west-east direction ~ 250 km and in the south-north direction ~ 670 km. The centers of these sources shifted by 4° to the more southern geomagnetic latitude ~ 63.5° (L ~ 5 Re) and moved westward with a velocity of ~ 1.7 km/s. We present estimates of the size of the magnetic force tube, in which the resonant MHD waves appeared, and the speed of its displacement in the equatorial plane of the magnetosphere.