Comment
doi: 10.1073/pnas.1208875109.
Epub 2012 Jul 18.
Helioseismology challenges models of solar convection
Affiliations
- PMID: 22814376
- PMCID: PMC3409781
- DOI: 10.1073/pnas.1208875109
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Comment
Helioseismology challenges models of solar convection
Proc Natl Acad Sci U S A.
.
No abstract available
Conflict of interest statement
The authors declare no conflict of interest.
Figures
Comparison of kinetic energy spectra 
of longitudinal solar velocities vs. spherical harmonic degree 
. The black curve above the gray area shows the observational upper limit from SDO/HMI helioseismology at radius 
and 1-day averaging (2). The red curve is from surface velocities measured by tracking granules using SDO/HMI intensity images (18). Notice the excess power at 
due to supergranulation. Results from snapshots of numerical simulations of convection sliced at 
are given by the blue and light blue curves. The blue curve shows the spectrum from an ASH spherical-shell simulation (12), and the light blue curve shows the spectrum from a stagger (16) near-surface radiative compressible simulation of size 
Mm3. The horizontal black line and associated arrow shows a theoretical lower limit based on global dynamics arguments (14), assuming mode equipartition over 
. We defined Eϕ at radius r such that 
, where 
is the longitudinal (prograde) component of the velocity field, and the expectation value is approximated by a horizontal average (consistent with ref. in the limit of large 
).
of longitudinal solar velocities vs. spherical harmonic degree . The black curve above the gray area shows the observational upper limit from SDO/HMI helioseismology at radius and 1-day averaging (2). The red curve is from surface velocities measured by tracking granules using SDO/HMI intensity images (18). Notice the excess power at due to supergranulation. Results from snapshots of numerical simulations of convection sliced at are given by the blue and light blue curves. The blue curve shows the spectrum from an ASH spherical-shell simulation (12), and the light blue curve shows the spectrum from a stagger (16) near-surface radiative compressible simulation of size Mm3. The horizontal black line and associated arrow shows a theoretical lower limit based on global dynamics arguments (14), assuming mode equipartition over . We defined Eϕ at radius r such that , where is the longitudinal (prograde) component of the velocity field, and the expectation value is approximated by a horizontal average (consistent with ref. in the limit of large ).Comment on
-
Anomalously weak solar convection.Proc Natl Acad Sci U S A. 2012 Jul 24;109(30):11928-32. doi: 10.1073/pnas.1206570109. Epub 2012 Jun 4. Proc Natl Acad Sci U S A. 2012. PMID: 22665774 Free PMC article.
References
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- Gilman PA. Fluid dynamics and MHD of the solar convection zone and tachocline: Current understanding and unsolved problems. Sol Phys. 2000;192:27–48.
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- Christensen-Dalsgaard J. Helioseismology. Rev Mod Phys. 2002;74:1073–1129.
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- Charbonneau P. Dynamo models of the solar cycle. Liv Rev Solar Phys. 2010;7:3.
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