Magnetotelluric micropulsations at widely separated stations

Magnetotelluric micropulsations were recorded simultaneously at Texas, Puerto Rico, and Trinidad, West Indies, during October 1962. Analysis of several data samples yielded information concerning the power spectrums of micropulsation activity and the coherency of signals recorded at the three locations. No frequency variation with latitude or longitude was observed. No significant diurnal frequency variation was noted, although a wide change in peak frequency was seen from day to day. The coherency analysis indicated that the signals at the three locations were consistently very similar and at times were nearly identical.