GPS RADIO INTERFEROMETRY OF TRAVELING IONOSPHERIC DISTURBANCES

This paper presents some results investigating the new possibilities o f radio interferometry of Travelling Ionospheric Disturbances (TIDs) t hat are based on exploiting standard measurements of transionospheric radio signal characteristics and coordinate-time measurements using du al-frequency multichannel receivers of the Global Positioning System ( GPS). A Statistical Angle-of-arrival and Doppler Method for GPS radio interferometry (SADM-GPS) is proposed for determining the characterist ics of the TIDs dynamics by measuring variations of GPS phase derivati ves with respect to time and spatial coordinates. These data are used to calculate corresponding values of the velocity vector, in view of a correction for satellite motions based on the current information ava ilable regarding the angular coordinates of the satellites. Subsequent ly, velocity and direction distributions are constructed and analyzed to verify the hypothesis of whether there is a predominant displacemen t. If it exists, then the pattern can be considered to be travelling, and the mean travel velocity can be determined from the velocity distr ibution. Through a computer simulation it was shown that multi-satelli te GPS radio interferometry in conjunction with the SADM-GPS algorithm allows the detection and measurement of the velocity vector of TIDs i n virtually the entire azimuthal range of possible TID;propagation dir ections. The use of the proposed method is exemplified by an investiga tion of TIDs during the solar eclipse of 9 March 1997, using the GPS-r adio interferometer GPSINT at Irkutsk. (C) 1998 Elsevier Science Ltd. All rights reserved.