Analysis of the 27-day cycle of the geomagnetic field during the past 50 years

Abstract

Phase and frequency variability of 27-day cycle, related with solar rotation, has been evaluated from the range of variations in the geomagnetic field recorded during the last 50 years at L'Aquila Geomagnetic Observatory (covering roughly 4.5 sunspot cycles). The magnetic field variations observed on the ground, generated by the Sun surface rotation, is mainly due to the non-symmetrical distribution of active regions over the Sun surface. In this presentation we show the connections between the Sun's rotation and the terrestrial magnetic field variations. The magnetic data recorded at L'Aquila Geomagnetic observatory (42° 23’ N, 13° 19’E, L-shell=1.6, corrected geomagnetic latitude: 36.3°, corrected geomagnetic longitude: 87.2.) from 1960 to 2010 and the SW were used to study the temporal changes of the amplitude of the 27-day variations of the Earth magnetic field.