Experimental Investigation of the Characteristics of Pc1 Micropulsation Propagation Using a Midlatitude Five-Station Receiving Network.

摘要

An experimental study has been made of the characteristics of the propagation of midlatitude Pc1 micropulsations for the purpose of assessing the applicability of the 0.5-2.0 Hz frequency band to naval communications. Naturally occurring hydromagnetic emissions were the object of study because no effective way of artificially generating these waves is known. Observations were made using a five-station receiving network stretching from New York to Florida and from Maryland to Illinois. All data were telemetered in real time over telephone data lines to NRL for centralized recording and analysis. Amplitude, spectral, and polarization characteristics are presented for the data analyzed. Cross-correlation was used to determine propagation time delays between sites. The time delays were used as input parameters for three methods of propagation analysis to determine the speed and direction of arrival of the Pc1 waves. The first analysis method considers the propagation to be that of a plane wave traveling over a flat Earth; the second method considers the propagation to be that of a plane wave traveling over a spherical earth. The third method (called the source location method) assumes that the wave front spreads radially over a spherical earth from a localized source. Of the three analysis methods, the source location method satisfied the data best, had smaller standard deviations for the values of propagation velocity determined, and was more consistent in computed direction of arrival. No case of east-to-west propagation was observed, but this is primarily due to the mid-latitude location of the observation sites.