The response of the ionospheric TEC on travelling convection vortices

Abstract

We examine the manifestation of Travelling Convection Vortices (TCV) in the ionosphere of the Earth in a form of fluctuations of its Total Electron Content (TEC). To detect TCV event we have used magnetometer data from the ground arrays CANMOS and CARISMA. TEC fluctuations were obtained by processing GNSS data from IGS and UNAVCO stations. The use of array of GPS receivers enables us to monitor the origin and dynamics of disturbance and also to obtain its physical parameters such as its amplitude and propagation speed along the ionosphere. For processing GPS data we have developed an algorithm that allows to detect isolated TEC fluctuations of specific duration and to find their location (and the corresponding time) on the map. In this way we successfully find a considerable agreement between data from ground-based magnetometers and ionospheric TEC data. The formation of TCV is observed almost simultaneously in both data time series and it is localized in a very small map region. We have also estimated the horizontal propagation speed of ionospheric disturbance. The calculated speed values (about some km per sec) are in agreement with expected velocities of the ionospheric projection of the solar wind flow around the magnetopause. The most interesting thing is that we can observe the formation of TCV in the ionospheric data while analyzing the amplitudes of disturbance. We also distinguish an origin of a probable TCV as a series of small scale TEC fluctuations. These results proved that GPS/TEC technique is sufficiently sensitive to monitor a formation and movement of TCV. The form of this disturbance is an isolated peak in a TECdata with a rather high amplitude. It reveals itself as a very fast TEC variation with a derivative up to 5 TECu/min and higher near a place of the TCV formation. Away from an “epicenter” of TCV-related disturbance its amplitude slowly decreases.