scholarly journals Weak influence of near-surface layer on solar deep convection zone revealed by comprehensive simulation from base to surface

2019 ◽  
Vol 5 (1) ◽  
pp. eaau2307 ◽  
Author(s):  
H. Hotta ◽  
H. Iijima ◽  
K. Kusano
Keyword(s):  
Convection Zone ◽  
Solar Surface ◽  
Deep Convection ◽  
Surface Region ◽  
Local Domain ◽  
Near Surface ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Weak Influence ◽  
The Magnetic Field

The solar convection zone is filled with turbulent convection in highly stratified plasma. Several theoretical and observational studies suggest that the numerical calculations overestimate the convection velocity. Since all deep convection zone calculations exclude the solar surface due to substantial temporal and spatial scale separations, the solar surface, which drives the thermal convection with efficient radiative cooling, has been thought to be the key to solve this discrepancy. Thanks to the recent development in massive supercomputers, we are successful in performing the comprehensive calculation covering the whole solar convection zone. We compare the results with and without the solar surface in the local domain and without the surface in the full sphere. The calculations do not include the rotation and the magnetic field. The surface region has an unexpectedly weak influence on the deep convection zone. We find that just including the solar surface cannot solve the problem.

scholarly journals Mean-Field Magnetohydrodynamics of the Solar Convection Zone

1976 ◽  
Vol 71 ◽  
pp. 305-321
Author(s):  
F. Krause
Keyword(s):  
Magnetic Field ◽  
Velocity Field ◽  
Convection Zone ◽  
Solar Surface ◽  
Mean Field ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Random Character ◽  
Physical Quantities ◽  
The Magnetic Field

Observations of the solar surface show that some of the physical quantities, especially the velocity field and the magnetic field, show random character.

scholarly journals Magnetoconvection Patterns in Rotating Convection Zones

1991 ◽  
Vol 130 ◽  
pp. 37-56
Author(s):  
Paul H. Roberts
Keyword(s):  
Convection Zone ◽  
Solar Surface ◽  
Giant Cells ◽  
Conclusive Evidence ◽  
The Other ◽  
The Sun ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Entire Thickness ◽  
Convective Motions

AbstractIn addition to the well-known granulation and supergranulation of the solar convection zone (the “SCZ”), the presence of so-called “giant cells” has been postulated. These are supposed span the entire thickness of the SCZ and to stretch from pole to pole in a sequence of elongated cells like a “cartridge belt” or a bunch of “bananas” strung uniformly round the Sun. Conclusive evidence for the existence of such giant cells is still lacking, despite strenuous observational efforts to find them. After analyses of sunspot motion, Ribes and others believe that convective motions near the solar surface occurs in a pattern that is the antithesis of the cartridge belt: a system of “toroidal” or “doughnut” cells, girdling the Sun in a sequence that extends from one pole to the other. Galloway, Jones and Roberts have recently tried to meet the resulting theoretical challenge, with the mixed success reported in this paper.

scholarly journals Simulating the Solar Dynamo

1993 ◽  
Vol 157 ◽  
pp. 111-121
Author(s):  
Axel Brandenburg
Keyword(s):  
Eddy Viscosity ◽  
Convection Zone ◽  
Transport Coefficients ◽  
Mean Field ◽  
Field Orientation ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Magnetic Diffusivity ◽  
The Magnetic Field

Mean-field and direct simulations of the hydrodynamics and hydromagnetics of the solar convection zone are discussed with the ultimate aim to understand the generation of differential rotation and magnetic fields. Various arguments constraining the values of the various turbulent diffusion coefficients are presented. It is suggested that the turbulent magnetic diffusivity is much smaller than the eddy viscosity which, in turn, is by up to a factor of ten smaller than the eddy conductivity. The magnetic field obtained from direct simulations is highly intermittent, and there is no clear systematic orientation of bipolar regions emerging from the convection zone. Various mechanisms that might cause such a field orientation are considered. Finally, the application of direct simulations to the determination of mean-field transport coefficients is emphasised.

scholarly journals Magnetic fields in the solar convection zone

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Yuhong Fan
Keyword(s):  
Magnetic Field ◽  
Convection Zone ◽  
Active Regions ◽  
Toroidal Magnetic Field ◽  
Near Surface ◽  
New Developments ◽  
Solar Convection Zone ◽  
Flux Tubes ◽  
Solar Convection ◽  
Dynamo Mechanism

AbstractIt has been a prevailing picture that active regions on the solar surface originate from a strong toroidal magnetic field stored in the overshoot region at the base of the solar convection zone, generated by a deep seated solar dynamo mechanism. This article reviews the studies in regard to how the toroidal magnetic field can destabilize and rise through the convection zone to form the observed solar active regions at the surface. Furthermore, new results from the global simulations of the convective dynamos, and from the near-surface layer simulations of active region formation, together with helioseismic investigations of the pre-emergence active regions, are calling into question the picture of active regions as buoyantly rising flux tubes originating from the bottom of the convection zone. This article also gives a review on these new developments.

scholarly journals Helioseismic Observations of Solar Convection Zone Dynamics

2010 ◽  
Vol 6 (S271) ◽  
pp. 15-22
Author(s):  
Frank Hill ◽  
Rachel Howe ◽  
Rudi Komm ◽  
Irene González Hernández ◽  
Shukur Kholikov ◽  
...  
Keyword(s):  
Large Scale ◽  
Convection Zone ◽  
Global Analysis ◽  
Torsional Oscillation ◽  
Temporal Variations ◽  
Flare Activity ◽  
Flux Transport ◽  
Near Surface ◽  
Solar Convection Zone ◽  
Solar Convection

AbstractThe large-scale dynamics of the solar convection zone have been inferred using both global and local helioseismology applied to data from the Global Oscillation Network Group (GONG) and the Michelson Doppler Imager (MDI) on board SOHO. The global analysis has revealed temporal variations of the “torsional oscillation” zonal flow as a function of depth, which may be related to the properties of the solar cycle. The horizontal flow field as a function of heliographic position and depth can be derived from ring diagrams, and shows near-surface meridional flows that change over the activity cycle. Time-distance techniques can be used to infer the deep meridional flow, which is important for flux-transport dynamo models. Temporal variations of the vorticity can be used to investigate the production of flare activity. This paper summarizes the state of our knowledge in these areas.

scholarly journals Distributions of the Sources of the Magnetic Field During the Double Magnetic Cycle

1998 ◽  
Vol 185 ◽  
pp. 463-464
Author(s):  
Elena E. Benevolenskaya
Keyword(s):  
Magnetic Field ◽  
Solar Magnetic Field ◽  
Convection Zone ◽  
Coronal Holes ◽  
Magnetic Cycle ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
The Magnetic Field ◽  
Dynamo Process ◽  
Longitudinal Structures

The longitudinal and latitudinal distributions of the solar magnetic field have been investigated by many authors see e.g. (Bumba and Howard 1969; Gaizauskas et. al. 1983). The main longitudinal structures such as active longitudes, sector boundaries in the solar wind, and coronal holes appear to be the consequence of non-symmetric magnetic modes (Stix 1971; Ivanova and Ruzmaikin 1977) and can be explained within the framework of dynamo models. According to these models, solar magnetic fields are generated by helicity and differential rotation in the solar convection zone (Parker 1979) and the linear dynamo process may generate a carrier frequency ωc (ωc = 2π/T, T = 22 yr

scholarly journals Can short time delays influence the variability of the solar cycle?

2010 ◽  
Vol 6 (S271) ◽  
pp. 288-296
Author(s):  
Laurène Jouve ◽  
Michael R. E. Proctor ◽  
Geoffroy Lesur
Keyword(s):  
Solar Cycle ◽  
Convection Zone ◽  
Mean Field ◽  
Period Doubling ◽  
Temporal Modulation ◽  
Solar Convection Zone ◽  
Flux Tubes ◽  
Solar Convection ◽  
Short Time ◽  
Period Doubling Bifurcations

AbstractWe present the effects of introducing results of 3D MHD simulations of buoyant magnetic fields in the solar convection zone in 2D mean-field Babcock-Leighton models. In particular, we take into account the time delay introduced by the rise time of the toroidal structures from the base of the convection zone to the solar surface. We find that the delays produce large temporal modulation of the cycle amplitude even when strong and thus rapidly rising flux tubes are considered. The study of a reduced model reveals that aperiodic modulations of the solar cycle appear after a sequence of period doubling bifurcations typical of non-linear systems. We also discuss the memory of such systems and the conclusions which may be drawn concerning the actual solar cycle variability.

scholarly journals Simulating Solar Global Magnetism in 3-D

2012 ◽  
Vol 10 (H16) ◽  
pp. 101-103
Author(s):  
A. S. Brun ◽  
A. Strugarek
Keyword(s):  
Magnetic Field ◽  
Recent Progress ◽  
Convection Zone ◽  
Thermal Structure ◽  
Solar Convection ◽  
Self Consistent ◽  
The Mean ◽  
The Magnetic Field

AbstractWe briefly present recent progress using the ASH code to model in 3-D the solar convection, dynamo and its coupling to the deep radiative interior. We show how the presence of a self-consistent tachocline influences greatly the organization of the magnetic field and modifies the thermal structure of the convection zone leading to realistic profiles of the mean flows as deduced by helioseismology.

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