scholarly journals On the Detection of Subphotospheric Convective Velocities and Temperature Fluctuations

1983 ◽  
Vol 66 ◽  
pp. 401-410
Author(s):  
D. O. Gough ◽  
J. Toomre
Keyword(s):  
Large Scale ◽  
Temperature Fluctuations ◽  
Wave Number ◽  
Convective Velocity ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Wave Patterns ◽  
Large Scale Flow ◽  
Low Amplitude ◽  
High Degree

AbstractA procedure is outlined for estimating the influence of large-scale convective eddies on the wave patterns of five-minute oscillations of high degree. The method is applied to adiabatic oscillations, with frequency ω and wave number k, of a plane-parallel polytropic layer upon which is imposed a low-amplitude convective flow. The distortion to the k – ω relation has two constituents: one depends on the horizontal component of the convective velocity and has a sign which depends on the sign of ω/k; the other depends on temperature fluctuations and is independent of the sign of ω/k. The magnitude of the distortion is just at the limit of present observational sensitivity. Thus there is reasonable hope that it will be possible to reveal some aspects of the large-scale flow in the solar convection zone

Large-scale Flow and Transport of Magnetic Flux in the Solar Convection Zone

2000 ◽  
Vol 179 ◽  
pp. 315-318
Author(s):  
P. Ambrož
Keyword(s):  
Velocity Field ◽  
Magnetic Flux ◽  
Large Scale ◽  
Activity Cycle ◽  
Horizontal Displacement ◽  
Horizontal Velocity ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Activity Cycles ◽  
Large Scale Flow

AbstractHorizontal large-scale velocity field describes horizontal displacement of the photospheric magnetic flux in zonal and meridian directions. The flow systems of solar plasma, constructed according to the velocity field, create the large-scale cellular-like patterns with up-flow in the center and the down-flow on the boundaries. Distribution of the largescale horizontal eddies (with characteristic scale length from 350 to 490 Mm) was found in the broad equatorial zone, limited by 60° latitude circles on both hemispheres. The zonal averages of the zonal and meridian velocities, and the total horizontal velocity for each Carrington rotation during the activity cycles no. 21 and 22 varies during the 11-yr activity cycle. Plot of RMS values of total horizontal velocity is shifted about 1.6 years before the similarly shaped variation of the magnetic flux.

Large Scale Flows in the Solar Convection Zone

2008 ◽  
Vol 144 (1-4) ◽  
pp. 151-173 ◽  
Author(s):  
Allan Sacha Brun ◽  
Matthias Rempel
Keyword(s):  
Large Scale ◽  
Convection Zone ◽  
Solar Convection Zone ◽  
Solar Convection

scholarly journals Subsurface Flows with Advancing Solar Cycle Using Dense-Pack Ring-Diagram Analyses

2001 ◽  
Vol 203 ◽  
pp. 211-214
Author(s):  
D. A. Haber ◽  
B. W. Hindman ◽  
J. Toomre ◽  
R. S. Bogart ◽  
F. Hill
Keyword(s):  
Solar Cycle ◽  
Large Scale ◽  
Doppler Velocity ◽  
Solar Convection Zone ◽  
Zonal Flows ◽  
Solar Convection ◽  
Doppler Imager ◽  
Ring Diagram ◽  
Subsurface Flows ◽  
The Mean

Ring-diagram analyses have become a powerful local helioseismic tool for studying large-scale flows in the upper solar convection zone. Using this technique on a dense-pack mosaic of many small regions extracted from the full-disk Doppler velocity data taken with the Michelson Doppler Imager (MDI) on SOHO, we study how the mean meridional and zonal flows vary with depth and latitude over the course of the advancing solar cycle from 1996 to 2000.

Temporal Variation of Large Scale Flows in the Solar Interior

2000 ◽  
Vol 179 ◽  
pp. 353-356
Author(s):  
Sarbani Basu ◽  
H. M. Antia
Keyword(s):  
Large Scale ◽  
Outer Part ◽  
Temporal Variations ◽  
Solar Interior ◽  
Short Term ◽  
Measured Velocity ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Doppler Imager ◽  
Ring Diagram

AbstractWe attempt to detect short-term temporal variations in the rotation rate and other large scale velocity fields in the outer part of the solar convection zone using the ring diagram technique applied to Michelson Doppler Imager (MDI) data. The measured velocity field shows variations by about 10m/s on the scale of few days.

scholarly journals Helicity–vorticity turbulent pumping of magnetic fields in the solar dynamo

2012 ◽  
Vol 8 (S294) ◽  
pp. 367-368
Author(s):  
V. V. Pipin
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Differential Rotation ◽  
Large Scale ◽  
Convection Zone ◽  
Solar Dynamo ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Large Scale Magnetic Field ◽  
Convective Motions

AbstractThe interaction of helical convective motions and differential rotation in the solar convection zone results in turbulent drift of a large-scale magnetic field. We discuss the pumping mechanism and its impact on the solar dynamo.

scholarly journals Round table discussion of session G: MHD convection and dynamos

2006 ◽  
Vol 2 (S239) ◽  
pp. 494-495
Author(s):  
Juri Toomre
Keyword(s):  
Large Scale ◽  
Round Table ◽  
Global Scale ◽  
Magnetic Activity ◽  
Small Scale ◽  
Round Table Discussion ◽  
Dynamo Action ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Prandtl Numbers

AbstractVigorous discussion ensued about conditions under which both small-scale and global-scale dynamo action would be realized within real stars where the flow fields are expected to be highly turbulent and the magnetic Prandtl numbers small. Our nearest star reminds us that intricate boundary-layer phenomena may have to also be considered, such as the presence of a tachocline of rotational shear at the base of the solar convection zone revealed by helioseismology, which suggests that an interface dynamo may be at work to produce the observed 22-year cycles of large-scale magnetic activity.

scholarly journals Large-scale flows and convection at the base of solar convection zone

2006 ◽  
Vol 2 (S239) ◽  
pp. 425-430
Author(s):  
Evgeniy Tikhomolov
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Convection Zone ◽  
Three Dimensional ◽  
Solar Radius ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Rotation Periods ◽  
Scale Temperature ◽  
Local Sound

AbstractDevelopment of convection in sun's outer shell is caused by reduction of effectiveness of energy transfer by radiation. Traditionally, models of solar convection are considered to be axisymmetric on the scale of solar radius. Such models provide basic understanding of convection under solar conditions. However, interpretation of a number of observable large-scale long-lived solar phenomena requires developing a non-axisymmetric approach. We present such a model in which large-scale non-axisymmetry is caused by large-scale flows such as Rossby waves and vortices. We model flows near the base of the solar convection zone. Anelastic approximation is used, which is valid for flow velocities much smaller than local sound speed. Our three-dimensional numerical simulations show that interaction of convection with large-scale flows leads to the establishment of non-axisymmetric large-scale temperature distribution. The interaction also gives rise to large-scale variations of penetration depth of convective plumes. Generation of the magnetic field by large-scale non-axisymmetric flows can explain such solar phenomena as complexes of activity, active longitudes, drifts of large-scale magnetic fields from equator to the poles, and appearance of distinct rotation periods of magnetic fields at some latitudes. We discuss a possibility of detection of large-scale non-axisymmetric flows and temperature distributions associated with them by the methods of helioseismology.

Depth Dependence on the Various Scale Lengths in a Quasi-Vitense Model of the Solar Convection Zone

1971 ◽  
Vol 2 (1) ◽  
pp. 48-50 ◽  
Author(s):  
B. E. Waters
Keyword(s):  
Vertical Velocity ◽  
Temperature Fluctuation ◽  
Convection Zone ◽  
Wave Number ◽  
Mixing Length ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Depth Dependence

As has been previously stated (van der Borght) the lengths l1, l2, l3 and l4 are functions of and so a discussion of these lengths is in fact a discussion of the f’s. For a first approach to a determination of these f’s, a standard Vitense2 model of the convection zone—with mixing length l, is used. We assume that l = H. The variables we need are kz, which are the vertical wave number associated with the characteristic eddy, the average vertical velocity, and the average (non-dimensional) temperature fluctuation. These quantities are approximated, using the following relations

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