Asymmetric Distribution of the Solar Photospheric Magnetic Field Values

Abstract

Understanding the characteristics of the solar magnetic field is essential for interpreting solar activities and dynamo. In this research, we investigated the asymmetric distribution of the solar photospheric magnetic field values, using synoptic charts constructed from space-borne high-resolution magnetograms. It is demonstrated that the Lorentzian function describes the distribution of magnetic field values in the synoptic charts much better than the Gaussian function, and this should reflect the gradual decay process from strong to weak magnetic fields. The asymmetry values are calculated under several circumstances, and the results generally show two periodicities related to the variation of the solar B${}_0$ angle and the solar cycle, respectively. We argue that it is the small-scale magnetic fields, the inclination of the solar axis, the emergence and evolution of magnetic flux, and the polar fields that are responsible for the features of asymmetry values. We further determined the polar field reversal time of solar cycles 23 and 24 with the flip of asymmetry values. Specifically, for cycle 24, we assert that the polar polarities of both hemispheres reversed at the same time - in March 2014; as to cycle 23, the reversal time of the S-hemisphere is March 2001, while the determination of the N-hemisphere is hampered by missing data.

arXiv comment12 pages, 8 figures; Accepted for publication in ApJ

References in corpus (18)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• The NumPy array: a structure for efficient numerical computation
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• The Solar Cycle
• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance
• The Magnetic Field in the Solar Atmosphere
• On Polar Magnetic Field Reversal and Surface Flux Transport During Solar Cycle 24
• Limits to solar cycle predictability: Cross-equatorial flux plumes
• The Sun's small-scale magnetic elements in Solar Cycle 23
• Solar cycle 24: an unusual polar field reversal
• Measurements of Photospheric and Chromospheric Magnetic Fields
• Unusual Polar Conditions in Solar Cycle 24 and their Implications for Cycle 25
• On Polar Magnetic Field Reversal in Solar Cycles 21, 22, 23, and 24
• Where are the solar magnetic poles?
• Asymmetric distribution of weak photospheric magnetic field values
• A new signal of the solar magnetic cycle: Opposite shifts of weak magnetic field distributions in the two hemispheres