THE ADVECTION OF SUPERGRANULES BY THE SUN'S AXISYMMETRIC FLOWS

Journal Article · Fri Dec 10 04:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/725/1/1082· OSTI ID:21474363

Hathaway, David H ^[1]; Williams, Peter E ^[2]; Rosa, Kevin Dela ^[3]; Cuntz, Manfred ^[4]

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1. NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)
2. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
3. School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213 (United States)
4. Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

We show that the motions of supergranules are consistent with a model in which they are simply advected by the axisymmetric flows in the Sun's surface shear layer. We produce a 10 day series of simulated Doppler images at a 15 minute cadence that reproduces most spatial and temporal characteristics seen in the SOHO/MDI Doppler data. Our simulated data have a spectrum of cellular flows with just two components-a granule component that peaks at spherical wavenumbers of about 4000 and a supergranule component that peaks at wavenumbers of about 110. We include the advection of these cellular components by the axisymmetric flows-differential rotation and meridional flow-whose variations with latitude and depth (wavenumber) are consistent with observations. We mimic the evolution of the cellular pattern by introducing random variations to the phases of the spectral components at rates that reproduce the levels of cross-correlation as functions of time and latitude. Our simulated data do not include any wave-like characteristics for the supergranules yet can reproduce the rotation characteristics previously attributed to wave-like behavior. We find rotation rates which appear faster than the actual rotation rates and attribute this to projection effects. We find that the measured meridional flow does accurately represent the actual flow and that the observations indicate poleward flow to 65{sup 0}-70{sup 0} latitude with equatorward countercells in the polar regions.

• OSTI ID: 21474363
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 725; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ADVECTION
ATMOSPHERES
AXIAL SYMMETRY
CRYOSPHERE
EVOLUTION
MAIN SEQUENCE STARS
MASS TRANSFER
MOTION
PHOTOSPHERE
POLAR REGIONS
ROTATION
SIMULATION
SOLAR ATMOSPHERE
SOLAR SYSTEM EVOLUTION
STAR EVOLUTION
STARS
STELLAR ATMOSPHERES
SUN
SYMMETRY
TIME DEPENDENCE