FLUCTUATIONS IN GEOMAGNETIC SECULAR VARIATION RATE ACCORDING TO DATA FROM THE GLOBAL NETWORK OF MAGNETIC OBSERVATORIES
A.V. Ladynin
Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
Keywords: Геомагнитное поле, скорость векового хода, флуктуации, периоды флуктуаций, амплитуды флуктуаций, колебания оси диполя и изменение его магнитного момента, Geomagnetic field, secular variation rate, fluctuation, fluctuation period, fluctuation amplitude, nutation of the dipole axis, magnetic dipole moment variation
Subsection: GEOPHYSICS
Abstract
The secular variation rate (SVR) of geomagnetic-field components (horizontal intensity H , vertical intensity Z , and inclination I) shows two types of fluctuations: with a short period (3 ± 0.15 years) and a long period (10-70 years). The amplitudes of the short-period fluctuations (SPFs) were estimated. The SPFs are uniform throughout the Earth, the Z and I SVR fluctuations are synchronous and have the same phases, and H SVR fluctuations are opposite in phase. Modeling of an eccentric-dipole field with a variable axial-pole latitude has shown that the SPFs in SVR are caused by the nutation of the dipole axis (and by the outer-core current systems responsible for the dipole field). Long-period fluctuations (LPFs) in SVR manifest themselves differently in different regions, and their nature is dominated by the effect of currents in the liquid core near the mantle.
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