2012/06/22 by Andrés Muñoz‐Jaramillo, Andrés Muñoz-Jaramillo, N. R. Sheeley +4 · 129 citations
Earth and Planetary Sciences · Physics and Astronomy · #Amplitude #Astronomy #Astrophysics #Atmospheric sciences #Flux (metallurgy) #Geophysics and Gravity Measurements #Ionosphere and magnetosphere dynamics #Magnetic field #Magnetic flux #Observatory #Optics #Physics #Polar #Solar and Space Plasma Dynamics #Solar cycle #Solar minimum #Solar observatory #Solar wind #Sunspot #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/753/2/146
published in The Astrophysical Journal 753(2), 146 (IOP Publishing) · 14 pages, 17 figures
openalex publication_date 2012/06/22 · arxiv created 2013/03/02 · arxiv updated 2013/03/05 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Although the Sun's polar magnetic fields are thought to provide important clues for understanding the 11 year sunspot cycle, including the observed variations of its amplitude and period, the current database of high-quality polar field measurements spans relatively few sunspot cycles. In this paper, we address this deficiency by consolidating Mount Wilson Observatory polar faculae data from four data reduction campaigns, validating it through a comparison with facular data counted automatically from Michelson Doppler Imager (MDI) intensitygrams, and calibrating it against polar field measurements taken by the Wilcox Solar Observatory and average polar field and total polar flux calculated using MDI line-of-sight magnetograms. Our results show that the consolidated polar facular measurements are in excellent agreement with both polar field and polar flux estimates, making them an ideal proxy to study the evolution of the polar magnetic field. Additionally, we combine this database with sunspot area measurements to study the role of the polar magnetic flux in the evolution of the heliospheric magnetic field (HMF). We find that there is a strong correlation between HMF and polar flux at solar minimum and that, taken together, polar flux and sunspot area are better at explaining the evolution of the HMF during the last century than sunspot area alone.