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
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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