East-West and North-South Attenuations of Long Radio Waves on the Pacific

A comparative study of low-frequency signals of high power stations in the Pacific area has been made, with particular reference to relative attenuation in north and south directions as compared with attenuattons in east and west directions. A comparison of observed field strengths in microvolts per meter with the results calculated by various proposed formulas has been made. While the agreement is none too good with any of the formulas, the results indicate that east and west attenuation is decidedly greater than north and south during the daylight hours in the fairly high latitudes. They also indicate that in comparing observed results with different transmission formulas due account must be taken of the type of experiments upon which the formulas in question were based. It is suggested that by the inclusion of terms in the formulas, depending upon both direction and latitude, it might be possible to construct or modify some of the existing formulas to fit the general case.