Long-period very low frequency emission pulsations

Abstract

Pulse trains with periods of the order of a minute occur in the natural VLF signals emitted in the exosphere. Composed of otherwise ordinary VLF emissions, the long-period pulses always rise in frequency. At magnetically conjugate points the long-period pulse signals are received simultaneously. The period of the pulsation events exhibits a latitude dependence, becoming longer at higher latitudes. On the basis of available data, a hypothesis associating hydromagnetic waves with emitting particles is offered to account for the observed properties of the pulsations.