Investigaciones sobre la variación secular geomagnética

Abstract

To exclude the solar R period influence, analysing the geomagnetic secular variation, the author has formerly turned in account (Bibl. 1) the series of 10 years mean values and stated existence of an approximate 50 years “terrestrial” period. In this paper the harmonic analysis for 44 values of each element of the Pilar Geomagnetic Observatory was used to characterise through the fourth harmonic the above mentioned solar influence. The curves of conjoined three harmonics show a general similarity. Also a “period” of 50-60 years can be seen. The parallelism of the fourth harmonic curve and the R-curve is evident. The change in geomagnetic force direction in the period of 1860-1948 for Cordoba, Argentina, is showed in Fig. 2.