Observations of total electron content perturbations on GPS signals caused by a ground level explosion

We have measured perturbations of electron density in the ionosphere caused by a ground level explosion with an energy release of 2 kt (8.5 x 10(12) J) using transmissions from Global Positioning System (GPS) satellites to monitor integrated electron density. The frequencies of the transmissions were 1575.42 MHz (L1) and 1227.60 MHz (L2). The detected perturbation showed a maximum excursion of 0.14 TEC units and had a duration of 80 s beginning at 565 s after the explosion. The acoustic disturbance necessary to produce such a perturbation is well modeled as an N wave with a dimension df 35 km and a relative amplitude of 12% propagating radially at a speed of 0.7 km/s. The majority of the TEC perturbation occurred at an altitude of approximately 200 km. (C) 1997 Elsevier Science Ltd.