Data obtained from the Australia Wide Array of Geomagnetic Stations (AWAGS) have provided a unique opportunity to investigate the spatial variation of long-period (Pc 5) ULF wave signal characteristics as a result of plasma waves in low latitudes. Pure state filtering techniques were applied in order to detect highly polarized Pc5 events and derive the wave signal parameters, i.e., the wave frequency, amplitude, polarization, and phase. The results indicate that the Pc 5 signal frequency was virtually independent of latitude and longitude, while the amplitude decreased considerably toward lower latitudes. The spatial variation of the signal polarization was found to be small. However, a statistical analysis of the signal polarization revealed a systematic diurnal variation. Counterclockwise sense of rotation (viewed in the direction of the ambient magnetic field) with the major axis of the polarization ellipse in the northeast quadrant was observed in the local morning, while clockwise sense of rotation with the polarization major axis aligned mainly in the north-south direction was seen in the local afternoon. Interstation phase analysis yielded small phase variations across the entire station array, indicating azimuthal wave numbers of 1<m<3. The signals appeared to propagate westward in the local morning sector, while eastward propagation prevailed in the local afternoon. The latitudinal phase variation was also very small, showing signals virtually in phase or with the lower-latitude stations leading slightly. These observations appear to be consistent with the magnetic ground signature of global compressional modes or large scale-cavity resonances trapped in the magnetosphere. ¿ American Geophysical Union 1993