Improvement of solar cycle prediction: Plateau of solar axial dipole moment

Abstract

Aims. We report the small temporal variation of the axial dipole moment near the solar minimum and its application to the solar cycle prediction by the surface flux transport (SFT) model. Methods. We measure the axial dipole moment using the photospheric synoptic magnetogram observed by the Wilcox Solar Observatory (WSO), the ESA/NASA Solar and Heliospheric Observatory Michelson Doppler Imager (MDI), and the NASA Solar Dynamics Observatory Helioseismic and Magnetic Imager (HMI). We also use the surface flux transport model for the interpretation and prediction of the observed axial dipole moment. Results. We find that the observed axial dipole moment becomes approximately constant during the period of several years before each cycle minimum, which we call the axial dipole moment plateau. The cross-equatorial magnetic flux transport is found to be small during the period, although the significant number of sunspots are still emerging. The results indicates that the newly emerged magnetic flux does not contributes to the build up of the axial dipole moment near the end of each cycle. This is confirmed by showing that the time variation of the observed axial dipole moment agrees well with that predicted by the SFT model without introducing new emergence of magnetic flux. These results allows us to predict the axial dipole moment in Cycle 24/25 minimum using the SFT model without introducing new flux emergence. The predicted axial dipole moment of Cycle 24/25 minimum is 60--80 percent of Cycle 23/24 minimum, which suggests the amplitude of Cycle 25 even weaker than the current Cycle 24. Conclusions. The plateau of the solar axial dipole moment is an important feature for the longer prediction of the solar cycle based on the SFT model.

5 pages, 3 figures, accepted for publication in A&A Letter

References in corpus (7)

• Effects of the scatter in sunspot group tilt angles on the large-scale magnetic field at the solar surface
• Calibrating 100 Years of Polar Faculae Measurements: Implications for the Evolution of the Heliospheric Magnetic Field
• Predicting the Amplitude and Hemispheric Asymmetry of Solar Cycle 25 with Surface Flux Transport
• Effects of Meridional Flow Variations on Solar Cycles 23 and 24
• Source of a Prominent Poleward Surge During Solar Cycle 24
• A theoretical study of the build-up of the Sun's polar magnetic field by using a 3D kinematic dynamo model
• Inflows towards active regions and the modulation of the solar cycle: a parameter study

Cited by in corpus (5)

• Thaddäus Derfflinger's sunspot observations during 1802-1824: A primary reference to understand the Dalton Minimum
• How good is the bipolar approximation of active regions for surface flux transport?
• Optimization of surface flux transport models for the solar polar magnetic field
• Revisiting Kunitomo's Sunspot Drawings during 1835-1836 in Japan
• Zonal harmonics of solar magnetic field for solar cycle forecast