World-Wide Effects of Hydromagnetic Waves Due to Argus

The Argus detonations in the ionosphere above the south Atlantic produced geomagnetic disturbances that propagated to almost all parts of the world. The geomagnetic variations, having a quasi-period of 1 to 3 seconds, were recorded principally by induction-type magnetometers and earth-current stations. We found two signals whose indicated velocities were of the order of 3000 and 700 km/sec. Amplitudes varied from 5 gammas (Antarctica) down to 0.002 gamma at our large loop in Arizona. The signal strength falls off rapidly as the direction of propagation deviates from the geomagnetic meridian.