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Stimulation of Pc 1 geomagnetic pulsations by naturally occurring repetitive VLF activity

1980; American Geophysical Union; Volume: 7; Issue: 10 Linguagem: Inglês

10.1029/gl007i010p00851

1944-8007

A. C. Fraser‐Smith, R. A. Helliwell,

Seismic Waves and Analysis

Several different mechanisms have been suggested for the natural stimulation of Pc 1 geomagnetic pulsation events. These mechanisms include hydromagnetic noise in the magnetosphere, bursts of radiation from high‐energy charged particles, or sferics from lightning discharges. Guided by the results of experiments to generate Pc 1 pulsations by VLF transmissions into the magnetosphere, and by the theory that has been developed in support of these experiments, we now propose a new mechanism: the stimulation of Pc 1 pulsation events by naturally occurring repetitive VLF signals. The VLF signals may be echoing whistlers, periodic chorus elements, or other periodic or quasiperiodic VLF wavetrains echoing along a geomagnetic field line. Preliminary support for this hypothesis is provided by a comparison of the Pc 1 pulsations and VLF activity occurring at Roberval, Quebec, during 9 intervals of simultaneous Pc 1 pulsation and VLF measurement.