2007•Yunnan Daxue xuebao. Shehui kexue banRequires access

Research on the geomagnetic main field periodicity

Guoming Gao

Abstract

Based on the data of the Bloxham Jackson Geomagnetic model(BJ for short) and the International Geomagnetic Reference Field(IGRF),the features of the geomagnetic main field periodicity are discussed.The results indicate that there is a periodicity about 60 years for the change rates of geomagnetic parameters,including geomagnetic moment,the spatial power spectrum and the average drift rate of spherical harmonic coefficients with different orders of the non-dipole magnetic field.And a 30-year periodicity is commonly available for the geomagnetic parameters and the average western drift rate considering the weight factors and the terms that related to n=2.Consequently,it can be confirmed that 60-year and 30-year are the main characteristic periods of geomagnetic secular variation.

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Key concepts: Earth's magnetic field, Geomagnetic secular variation, Secular variation, Ionospheric dynamo region, Geophysics, Ring current, Field (mathematics), Moment (physics)