Calibrating 100 Years of Polar Faculae Measurements: Implications for the Evolution of the Heliospheric Magnetic Field

Abstract

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 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.

arXiv comment14 pages, 17 figures

References in corpus (3)

• Predicting solar cycle 24 with a solar dynamo model
• A homogeneous database of sunspot areas covering more than 130 years
• Heliospheric Magnetic Field 1835-2009

Cited by in corpus (57)

• The Solar Cycle
• Solar cycle prediction
• Prediction of the strength and timing of sunspot cycle 25 reveal decadal-scale space environmental conditions
• Predicting the Sun's Polar Magnetic Fields with a Surface Flux Transport Model
• Solar Cycle Propagation, Memory, and Prediction: Insights from a Century of Magnetic Proxies
• Progress in Solar Cycle Predictions: Sunspot Cycles 24-25 in Perspective
• On Polar Magnetic Field Reversal and Surface Flux Transport During Solar Cycle 24
• Sympathetic Magnetic Breakout Coronal Mass Ejections from Pseudostreamers
• The cause of the weak solar cycle 24
• Hemispheric Coupling: Comparing Dynamo Simulations and Observations
• Effects of Meridional Flow Variations on Solar Cycles 23 and 24
• Forecasting Solar Cycle 25 using Deep Neural Networks
• Hemispheric sunspot numbers 1874--2020
• Solar cycle 24: an unusual polar field reversal
• Double-peaks of the solar cycle: An explanation from a dynamo model
• Solar cycle indices from the photosphere to the corona: measurements and underlying physics
• Improvement of solar cycle prediction: Plateau of solar axial dipole moment
• Nonlinear mechanisms that regulate the solar cycle amplitude
• Polar Network Index as a magnetic proxy for the solar cycle studies
• Physical Models for Solar Cycle Predictions
• A Three-Dimensional Babcock-Leighton Solar Dynamo Model: Initial Results with Axisymmetric Flows
• A theoretical study of the build-up of the Sun's polar magnetic field by using a 3D kinematic dynamo model
• Neural Network Forecast of the Sunspot Butterfly Diagram
• Predicting solar surface large-scale magnetic field of Cycle 24
• The polar precursor method for solar cycle prediction: comparison of predictors and their temporal range
• Using the Dipolar and Quadrupolar Moments to Improve Solar-Cycle Predictions Based on the Polar Magnetic Fields
• How many active regions are necessary to predict the solar dipole moment?
• Precursors of an upcoming solar cycle at high latitudes from coronal green line data
• Torus-Stable Zone Above Starspots
• A New Formula for Predicting Solar Cycles
• A 3D kinematic Babcock Leighton solar dynamo model sustained by dynamic magnetic buoyancy and flux transport processes
• Sunspot number second differences as a precursor of the following 11-year sunspot cycle
• Medium-term predictions of F10.7 and F30 cm solar radio flux with the adaptive Kalman filter
• Another Mini Solar Maximum in the Offing: A Prediction for the Amplitude of Solar Cycle 25
• Long-Term Evolution of the Sun's magnetic field during Cycles 15--19 based on their proxies from Kodaikanal Solar Observatory
• The Association of Polar Faculae with Polar Magnetic Patches Examined with Hinode Observations
• Solar activity simulation and forecast with a flux-transport dynamo
• Predicting the Timing of the the Solar Cycle 25 Polar Field Reversal
• Effect of morphological asymmetry between leading and following sunspots on the prediction of solar cycle activity
• Is hemispheric asymmetry in the sunspot cycle solely governed by polar flux imbalance in the previous cycle?
• Time-Latitude Distribution of Prominences for 10 Solar Cycles: A study using Kodaikanal, Meudon and Kanzelhohe Data
• Spatial-temporal forecasting the sunspot diagram
• Incorporating Surface Convection into a 3D Babcock-Leighton Solar Dynamo Model
• Beyond the mini-solar maximum of solar cycle 24: Declining solar magnetic fields and the response of the terrestrial magnetosphere
• Maximal growth rate of the ascending phase of a sunspot cycle for predicting its amplitude
• Impact of rogue active regions on hemispheric asymmetry
• Algebraic Quantification of the Contribution of Active Regions to the Sun's Dipole Moment: Applications to Century-scale Polar Field Estimates and Solar Cycle Forecasting
• The 2019 July 2 Total Solar Eclipse: Prediction of the Coronal Magnetic Field Structure and Polarization Characteristics
• Minimal Roles of Solar Subsurface Meridional Flow in the distributed-shear Babcock-Leighton Dynamo
• Latitudinal Distribution of the Photospheric Magnetic Fields of Different Magnitudes
• Polar cap magnetic field reversals during solar grand minima: could pores play a role?
• Two New Methods for Counting and Tracking the Evolution of Polar Faculae
• Extreme Fluctuations in the Sun's Activity over the Modern Maximum: Understanding the Enigmatic Solar Cycles 19-20
• Using Polar Faculae to Determine the Sun's High-Latitude Rotation Rate. I. Techniques and Initial Measurements
• Solar Cycle Prediction: Challenges, Progress, and Future Perspectives
• IAU commission 10 "Solar Activity": Legacy report and triennial report for 2012-2015
• The Sun's polar magnetic field: datasets, proxies and theoretical issues