Detection of ionospheric perturbations using dense GPS arrays

Summary form only given. Vertical motions of the Earth´s surface excite atmospheric infrasonic acoustic and gravity waves that propagate laterally and upward away from the source. These perturbations eventually reach the ionospheric layers, where the coupling between the neutral atmosphere and ionized plasma results in fluctuations of the ionospheric electron density. Dual-frequency Global Positioning System (GPS) data provide a straightforward means of measuring the ionospheric electron content. The development of permanent networks of densely spaced and continuously recording GPS stations provides the opportunity to investigate ionospheric perturbations and their characteristics with great detail. We show the possibilities offered by the Southern California Integrated GPS Network (SCIGN), a densely spaced GPS array of 250 ground stations centered on the Los Angeles area, to detect ionospheric perturbations. We show how methods derived from seismological array processing techniques can be used to determine basic properties of the perturbation, such as its propagation azimuth and velocity.