Predicting the Sun's Polar Magnetic Fields With a Surface Flux Transport Model

Upton, Lisa; Hathaway, David H.

doi:10.1088/0004-637x/780/1/5

Cited by 138 publications

(114 citation statements)

References 33 publications

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“…During minimum years the vantage point effect is at least partly due to the latitudinally varying tilt of the high-latitude fields (Ulrich & Tran 2013), but appears in a different way in different data sets. Recently it has been shown that the vantage point effect appears very weakly, if at all, in the HMI data (Upton & Hathaway 2014). Accordingly, it may also depend on spatial resolution, the noise level of high-latitude measurements, and the errors in the calculation of field strength using different spectral lines.…”

Section: Measuring High-latitude Fieldsmentioning

confidence: 99%

Photospheric and coronal magnetic fields in six magnetographs

Virtanen

Мурсула

2016

A&A

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Aims. We study the long-term evolution of photospheric and coronal magnetic fields and the heliospheric current sheet (HCS), especially its north-south asymmetry. Special attention is paid to the reliability of the six data sets used in this study and to the consistency of the results based on these data sets. Methods. We use synoptic maps constructed from Wilcox Solar Observatory (WSO), Mount Wilson Observatory (MWO), Kitt Peak (KP), SOLIS, SOHO/MDI, and SDO/HMI measurements of the photospheric field and the potential field source surface (PFSS) model. Results. The six data sets depict a fairly similar long-term evolution of magnetic fields and the heliospheric current sheet, including polarity reversals and hemispheric asymmetry. However, there are time intervals of several years long, when first KP measurements in the 1970s and 1980s, and later WSO measurements in the 1990s and early 2000s, significantly deviate from the other simultaneous data sets, reflecting likely errors at these times. All of the six magnetographs agree on the southward shift of the heliospheric current sheet (the so-called bashful ballerina phenomenon) in the declining to minimum phase of the solar cycle during a few years of the five included cycles. We show that during solar cycles 20-22, the southward shift of the HCS is mainly due to the axial quadrupole term, reflecting the stronger magnetic field intensity at the southern pole during these times. During cycle 23 the asymmetry is less persistent and mainly due to higher harmonics than the quadrupole term. Currently, in the early declining phase of cycle 24, the HCS is also shifted southward and is mainly due to the axial quadrupole as for most earlier cycles. This further emphasizes the special character of the global solar field during cycle 23.

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Section: Measuring High-latitude Fieldsmentioning

confidence: 99%

Photospheric and coronal magnetic fields in six magnetographs

Virtanen

Мурсула

2016

A&A

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“…Starting from the pioneering work of Wang et al (1989b,a), the surface flux transport (SFT) model has been made more sophisticated in several recent studies (van Ballegooijen et al 1998;Schrijver et al 2002;Baumann et al 2004Baumann et al , 2006Cameron et al 2010;Jiang et al 2014a; Upton & Hathaway 2014;Jiang et al 2015). In this model, recently reviewed by Jiang et al (2014b), one can study in detail how individual sunspot pairs contribute in building up the poloidal field and can address such questions as to how this process depends on such factors as the latitudinal positions of the sunspot pairs and the distribution in their tilt angles.…”

Section: Introductionmentioning

confidence: 99%

A Theoretical Study of the Build-Up of the Sun’s Polar Magnetic Field by Using a 3d Kinematic Dynamo Model

Hazra

Choudhuri

Miesch

2017

ApJ

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We develop a three-dimensional kinematic self-sustaining model of the solar dynamo in which the poloidal field generation is from tilted bipolar sunspot pairs placed on the solar surface above regions of strong toroidal field by using the SpotMaker algorithm, and then the transport of this poloidal field to the tachocline is primarily caused by turbulent diffusion. We obtain a dipolar solution within a certain range of parameters. We use this model to study the build-up of the polar magnetic field and show that some insights obtained from surface flux transport (SFT) models have to be revised. We present results obtained by putting a single bipolar sunspot pair in a hemisphere and two symmetrical sunspot pairs in two hemispheres.We find that the polar fields produced by them disappear due to the upward advection of poloidal flux at low latitudes, which emerges as oppositely-signed radial flux and which is then advected poleward by the meridional flow. We also study the effect that a large sunspot pair, violating Hale's polarity law would have on the polar field. We find that there would be some effect-especially if the anti-Hale pair appears at high latitudes in the mid-phase of the cycle-though the effect is not very dramatic.

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“…This entire process is better known as the Babcock-Leighton (BL) mechanism (Babcock 1961;Leighton 1969). The SFT models (Wang et al 1989(Wang et al , 2000van Ballegooijen et al 1998;Schrijver 2001;Mackay et al 2002aMackay et al , 2002bCameron et al 2010;Upton & Hathaway 2014;Hickmann et al 2015) are quite successful in capturing the physics of the BL mechanism. For the constant diffusivity, the magnetic field evolution on the solar surface is governed by the magnetic induction equation,…”

Section: Sft Methodologymentioning

confidence: 99%

The Large-scale Coronal Structure of the 2017 August 21 Great American Eclipse: An Assessment of Solar Surface Flux Transport Model Enabled Predictions and Observations

Nandy

Bhowmik

Yeates

et al. 2018

ApJ

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractOn 2017 August 21, a total solar eclipse swept across the contiguous United States, providing excellent opportunities for diagnostics of the Sun's corona. The Sun's coronal structure is notoriously difficult to observe except during solar eclipses; thus, theoretical models must be relied upon for inferring the underlying magnetic structure of the Sun's outer atmosphere. These models are necessary for understanding the role of magnetic fields in the heating of the corona to a million degrees and the generation of severe space weather. Here we present a methodology for predicting the structure of the coronal field based on model forward runs of a solar surface flux transport model, whose predicted surface field is utilized to extrapolate future coronal magnetic field structures. This prescription was applied to the 2017 August 21 solar eclipse. A post-eclipse analysis shows good agreement between model simulated and observed coronal structures and their locations on the limb. We demonstrate that slow changes in the Sun's surface magnetic field distribution driven by long-term flux emergence and its evolution governs large-scale coronal structures with a (plausibly cycle-phase dependent) dynamical memory timescale on the order of a few solar rotations, opening up the possibility for large-scale, global corona predictions at least a month in advance.

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Predicting the Sun's Polar Magnetic Fields With a Surface Flux Transport Model

Cited by 138 publications

References 33 publications

Photospheric and coronal magnetic fields in six magnetographs

Photospheric and coronal magnetic fields in six magnetographs

A Theoretical Study of the Build-Up of the Sun’s Polar Magnetic Field by Using a 3d Kinematic Dynamo Model

The Large-scale Coronal Structure of the 2017 August 21 Great American Eclipse: An Assessment of Solar Surface Flux Transport Model Enabled Predictions and Observations

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