scholarly journals Uniting The Sun’s Hale Magnetic Cycle and ‘Extended Solar Cycle’ Paradigms

2021 ◽  
Author(s):  
Scott W. McIntosh ◽  
Phillip H. Scherrer ◽  
Lief Svalgaard ◽  
Robert J. Leamon
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Large Scale ◽  
Sunspot Cycle ◽  
Solar Observatory ◽  
Solar Photosphere ◽  
Synoptic Scale ◽  
Predictive Capability ◽  
Large Scale Magnetic Field ◽  
First Time

Abstract Through meticulous daily observation of the Sun’s large-scale magnetic field the Wilcox Solar Observatory has catalogued two magnetic (Hale) cycles of solar activity. Those two (∼22-year long) Hale cycles have yielded four (∼11-year long) sunspot cycles-21 through 24. Recent research has highlighted the persistence of the “Extended Solar Cycle” (ESC) and its connection to the fundamental Hale Cycle-albeit through a host of proxies resulting from image analysis of the solar photosphere, chromosphere and corona. This Letter presents, for the first time, a direct mapping between the ESC, the Sun’s toroidal magnetic field evolution of the Hale Cycle. As Sunspot Cycle 25 begins to accelerate its growth, interest in mapping the Hale and Extended cycles could not be higher given potential predictive capability that synoptic scale observations can provide.

scholarly journals Reconstruction of Sun-as-Star Magnetic Field Structure and Evolution Using Filament Observations

1998 ◽  
Vol 167 ◽  
pp. 493-496
Author(s):  
Dmitri I. Ponyavin
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Large Scale ◽  
Solar Magnetic Field ◽  
Close Association ◽  
Field Structure ◽  
The Sun ◽  
Magnetic Field Structure ◽  
Large Scale Magnetic Field ◽  
Field Organization

AbstractA technique is used to restore the magnetic field of the Sun viewed as star from the filament distribution seen on Hα photographs. For this purpose synoptic charts of the large-scale magnetic field reconstructed by the McIntosh method have been compared with the Sun-asstar solar magnetic field observed at Stanford. We have established a close association between the Sun-as-star magnetic field and the mean magnetic field inferred from synoptic magnetic field maps. A filtering technique was applied to find correlations between the Sun-as-star and large-scale magnetic field distributions during the course of a solar cycle. The correlations found were then used to restore the Sun-as-star magnetic field and its evolution in the late 1950s and 1960s, when such measurements of the field were not being made. A stackplot display of the inferred data reveals large-scale magnetic field organization and evolution. Patterns of the Sun-as-star magnetic field during solar cycle 19 were obtained. The proposed technique can be useful for studying the solar magnetic field structure and evolution during times with no direct observations.

scholarly journals Numerical Simulations of Large-scale Solar Magnetic Fields

1985 ◽  
Vol 38 (6) ◽  
pp. 999 ◽  
Author(s):  
CR DeVore ◽  
NR Sheeley Jr ◽  
JP Boris ◽  
TR Young Jr ◽  
KL Harvey
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Large Scale ◽  
Sunspot Cycle ◽  
Active Regions ◽  
The Sun ◽  
Solar Magnetic Fields ◽  
Field Patterns ◽  
Large Scale Magnetic Field ◽  
The Magnetic Field

We have solved numerically a transport equation which describes the evolution of the large-scale magnetic field of the Sun. Data derived from solar magnetic observations are used to initialize the computations and to account for the emergence of new magnetic flux during the sunspot cycle. Our objective is to assess the ability of the model to reproduce the observed evolution of the field patterns. We discuss recent results from simulations of individual active regions over a few solar rotations and of the magnetic field of the Sun over sunspot cycle 21.

Cosmic-Ray Transport in Heliospheric Magnetic Structures. III. Implications of Solar Magnetograms for the Drifts of Cosmic Rays

2021 ◽  
Vol 922 (2) ◽  
pp. 124
Author(s):  
Andreas Kopp ◽  
Jan Louis Raath ◽  
Horst Fichtner ◽  
Marius S. Potgieter ◽  
Stefan E. S. Ferreira ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Cosmic Rays ◽  
Boundary Conditions ◽  
Large Scale ◽  
Cosmic Ray ◽  
Magnetic Polarity ◽  
Solar Observatory ◽  
Field Polarity ◽  
Heliospheric Magnetic Field

Abstract The transport of energetic particles in the heliosphere is reviewed regarding the treatment of their drifts over an entire solar cycle including the periods around solar maximum, when the tilt angles of the heliospheric current sheet increase to large values and the sign of the magnetic polarity changes. While gradient and curvature drifts are well-established elements of the propagation of cosmic rays in the heliospheric magnetic field, their perturbation by the solar-activity-induced large-scale distortions of dipole-like field configurations and by magnetic turbulence is an open problem. Various empirical or phenomenological approaches have been suggested, but either lack a theory-based motivation or have been shown to be incompatible with measurements. We propose a new approach of more closely investigating solar magnetograms obtained from GONG maps, leading to a new definition of (i) tilt angles that may exceed those provided by the Wilcox Solar Observatory during high activity and of (ii) a “noninteger sign” that can be used to reduce the drifts during these periods as well as to provide a refinement of the magnetic field polarity. The change of sign from A < 0 to A > 0 of solar cycle 24 can be in this way localized to occur between Carrington Rotations 2139 and 2140 in mid 2013. This treatment is fully consistent in the sense that the transport modeling uses the same input data to formulate the boundary conditions at the heliobase as do the magnetohydrodynamic models of the solar wind and the embedded heliospheric magnetic field that exploit solar magnetograms as inner boundary conditions.

scholarly journals The Large-scale Magnetic Field in the Global Solar Cycle: Observational Aspects

1991 ◽  
Vol 130 ◽  
pp. 213-217
Author(s):  
V.I. Makarov ◽  
K.R. Sivaraman
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
High Latitude ◽  
Weak Magnetic Field ◽  
Large Scale ◽  
Meridional Flow ◽  
The Sun ◽  
Low Latitude ◽  
Large Scale Magnetic Field ◽  
Global Cycle

Abstract The global solar cycle is considered as an interaction of 3 types of activity: at low-latitude (sunspots), at high-latitude (polar faculae) and the weak magnetic field. The properties of single and 3-fold reversals of the polar magnetic field are considered. The variation spectrum of the large-scale magnetic field of the Sun is analyzed in the range of 1–30 nHz. A dependence between the rate of a poleward meridional flow and phase of the global cycle is discussed.

scholarly journals Dynamics of Large-Scale Magnetic Field Evolution During Solar Cycle 20

1980 ◽  
Vol 91 ◽  
pp. 25-28
Author(s):  
Patrick S. McIntosh
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Large Scale ◽  
Solar Rotation ◽  
Coronal Holes ◽  
Solar Magnetic Fields ◽  
Magnetic Pattern ◽  
Large Scale Magnetic Field ◽  
Convergence And Divergence

The evolution of large-scale solar magnetic fields has been studied for a complete solar cycle using the atlas of H-alpha synoptic charts for 1964-1974. The results include: a unique magnetic pattern coinciding with major coronal holes; variations in the rate of solar rotation through the solar cycle; discovery of convergence and divergence among long-lived magnetic patterns; periodic discontinuities in the organization of large-scale magnetic fields; and a new cause for coronal transients.

scholarly journals Explaining the Hemispheric Pattern of Filament Chirality

2013 ◽  
Vol 8 (S300) ◽  
pp. 172-175
Author(s):  
Duncan H. Mackay ◽  
Anthony R. Yeates
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Southern Hemisphere ◽  
Large Scale ◽  
Detailed Comparison ◽  
Data Driven ◽  
Temporal Dependence ◽  
Large Scale Magnetic Field ◽  
Solar Filaments ◽  
Global Magnetic Field

AbstractSolar filaments are known to exhibit a hemispheric pattern in their chirality, where dextral/sinistral filaments dominate in the northern/southern hemisphere. We show that this pattern may be explained through data driven 3D global magnetic field simulations of the Sun's large-scale magnetic field. Through a detailed comparison with 109 filaments over a 6 month period, the model correctly reproduces the filament chirality and helicity with a 96% agreement. The data driven simulation is extended to run over a full solar cycle, where predictions are made for the spatial and temporal dependence of the hemispheric pattern over the solar cycle.

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