太陽磁気多重極子軸対称成分の長周期変動

概要

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We study long-term variations of axially-symmetric components of solar magnetic multiplepoles during three (21, 22, 23) solar activity cycles about in 35 years from 1615 Carrington rotation through 2089 Carrington rotation. We use the RF-model, the potential field and source surface model, for the coronal magnetic field. The magnetic field is assumed to be the potential field and can be expanded into a spherical harmonic series. It is found that the coefficient of the axial dipole moment, g01, shows a similar periodic sinusoidal variation along with the solar activity cycle. It is also found what g05 shows a similar periodic sinusoidal variation to the one of g01. Althogh the sinusoidal variations of g01 and ones of g05 are almost out of phase, the polarity change of g05 is followed by the one of g05. This phenomenon can be used to predict the time when the solar magnetic field shows polarity reversal.