Chief results of a preliminary analysis of the Earth's magnetic field for 1922—No. 1.

Abstract

From a new analysis of the Earth's magnetic field for 1922, made as free as possible without assumptions as to the composing systems and restricted to the region of the Earth (86 per cent), from 60°N to 60°S, the author concludes that for a satisfactory representation of the observed data it is necessary to recognize the existence of an internal magnetic system, I, an external system, E, and a non‐potential system, N, or of three equivalent systems, X, Y, Z. The system I constitutes about 94 per cent of the total field, and E and N each about half of the balance of 6 per cent.He shows that the magnetic secular variation system is as complex as the Earth's total magnetic field existing at any one time, and that in addition to changes in the direction of magnetization with the lapse of time there is also a change in the average equivalent intensity of magnetization. The latter quantity has been steadily diminishing during the past 80 years at the average annual rate of about 1/1,500 part.For further statement of results, reference may be made to the “Summary of Chief Conclusions” at the close of the paper.