Determining parameters of large-scale traveling ionospheric disturbances of auroral origin using GPS-arrays

The intention in this paper is to investigate the form and dynamics of larg e-scale traveling ionospheric disturbances (LS TIDs) of auroral origin. We have devised a technique for determining LS TID parameters using GPS-arrays whose elements can be selected from a large set of GPS stations forming pa rt of the International GPS Service network. The method was used to determi ne LS TID parameters during a strong magnetic storm of September 25, 1998. The North-American sector where many GPS stations are available, and also t he time interval 00:00-06:00 UT characterized by a maximum value of the der ivative Dst were used in the analysis. The study revealed that this period of time was concurrent with the formation of the main ionospheric trough wi th a conspicuous southward wall in the range of geographic latitudes 50-60 degrees and the front width of no less than 7500 kin. The auroral disturban ce-induced large-scale solitary wave with a duration of about 1 h and the f ront width of at least 3700 km propagated in the equatorward direction to a distance of no less than 2000-3000 km with the mean velocity of about 300 m/s. The wave front behaved as if it 'curled' to the west in longitude wher e the local time was around afternoon. Going toward the local nighttime, th e propagation direction progressively approximated an equatorward direction . (C) 2000 Elsevier Science Ltd. All rights reserved.