Pulse modulation of the U.S. Naval VLF transmitter at Cutler, Maine, has been explored as a means of stimulating geomagnetic micropulsations. In a month-long experiment the transmitter was square wave modulated at frequencies of 0.2, 1, and 5 Hz with a network of sensitive magnetometers employed as micropulsation detectors. While the experimental results are not statistically conclusive, micropulsations occurred on several occasions at harmonics of the transmitter modulation frequency. Evidence is adduced to suggest that micropulsations may be stimulated by this means under quiet conditions immediately following geomagnetically active days. |