Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute,...
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![Page 1: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/1.jpg)
Numerical Simulations of Supergranulation and
Solar Oscillations
Åke Nordlund
Niels Bohr Institute, Univ. of Copenhagen
with
Bob Stein (MSU)
David Benson, Dali Georgobiani
Sasha Kosovichev, Junwei Zhao (Stanford)
![Page 2: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/2.jpg)
Experiment settings: Code
Staggered mesh code conservative, with radiative transfer
fast – about 5 CPU-microseconds / mesh-update includes 4-bin radiative transfer
massively parallel OpenMP up to about 250 CPUs MPI up to thousands of CPUs (just developed) Hybrid MPI/OMP for clusters with shared mem. nodes
e.g. DCSC/KU: 118 nodes x dual-CPUs x dual core AMD = 472 cores (corresponds to ~90 million zone-updates / sec)
![Page 3: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/3.jpg)
Stagger Code:Scaling on Columbia (Altix)
With OpenMP
With MPI
Size N-cpu µsec/pnt
125x500x125 1 5.9
250x500x250 64 8.6
500x500x500 64 7.8
500x500x500 125 9.3
500x500x500 250 11.9
Size N-cpu µsec/pnt
250x500x250 1 4.3
250x500x250 50 4.7
500x500x500 50 5.3
500x500x500 100 6.1
500x500x500 250 6.7
![Page 4: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/4.jpg)
Supergranulation Simulation48 Mm wide x 20 Mm deep
63 hours (1.3 turnover time) f-plane rotation (surface shear layer) No magnetic field (yet) Low resolution:
• 100 km horizontal, • 12-70 km vertical
![Page 5: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/5.jpg)
Mean Atmosphere: Ionization of Hydrogen and Helium
![Page 6: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/6.jpg)
What can we learn?
Use the model and data as a test bed SOHO/MDI synthetic data
what does SOHO/MDI actually measure, and how well? Local helioseismology
what do the various methods measure, and how well?
Nature of the flow field What is ‘supergranulation’? How does it fit in with larger & smaller scales?
![Page 7: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/7.jpg)
Data sets available onStanford Helioseismology Archive
![Page 8: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/8.jpg)
Upflows at surface come from small area at bottom (left)Downflows at surface converge to supergranule boundaries (right)
![Page 9: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/9.jpg)
Animation
![Page 10: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/10.jpg)
Time evolution at various depths
![Page 11: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/11.jpg)
Velocity at the same depths
![Page 12: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/12.jpg)
The solar velocity spectrum
Power spectra are often plotted log-log, which means the power per unit x-axis is really k P(k), rather than just P(k)!
![Page 13: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/13.jpg)
Solar velocity spectrum
MDI doppler (Hathaway) TRACE
correlation tracking (Shine)
MDI correlation tracking (Shine)
3-D simulations (Stein & Nordlund)
V ~ k
V~k-1/3
constantV
Velocity spectrum:
v(k) = (k P(k))1/2
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Rotation subtracted solar Doppler image
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Ni 6768 response function
![Page 16: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/16.jpg)
simulation MDI
k- Diagram
![Page 17: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/17.jpg)
Sub-sonic filtering
~ 7 km/s~ 7 km/s
![Page 18: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/18.jpg)
P-mode power (red), convective power (black) – time average (blue)
Hi-res MDI
Note that it matters very much how one
computes power spectra
![Page 19: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/19.jpg)
Velocity spectrumonly distinct scale is granulation
Vhoriz (sim)
Vz(sim)
V MDI
- - - - convection
…. oscillations
![Page 20: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/20.jpg)
A continuous solar velocity spectrum!
Supergranulation may stand out a little
But the flow is nearly scale-invariant amplitudes scale inversely with size lifetimes scale with the square of the size
![Page 21: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/21.jpg)
A Nearly Scale Free Spectrum!Doppler Image of the Sun (SOHO/MDI)
![Page 22: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/22.jpg)
Solar horizontal velocity (observed)Scales differ by factor 2 – which is which?
400 Mm
200 Mm
100 Mm
50 Mm
![Page 23: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/23.jpg)
Solar horizontal velocity (model)Scales differ by factor 2 – which is which?
24 Mm12 Mm
6 Mm3 Mm
![Page 24: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/24.jpg)
Solar velocity spectrum
![Page 25: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/25.jpg)
Time-Distance Diagram
![Page 26: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/26.jpg)
f-mode Travel Times vs Simulated Flow Fields (divergence)
Right side image shows the f-mode outgoing and ingoing travel time differences, and the left side image shows the divergence computed from simulation. (From Junwei Zhao)
![Page 27: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/27.jpg)
f-mode Travel Times vs Simulated Flow Fields (Horizontal)
Right side image shows the f-mode north-going and south-going travel time differences, and the left side image shows the Vn-s
averaged from simulation. (From Junwei Zhao & Aaron Birch)
![Page 28: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/28.jpg)
Local Correlation Tracking
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Sunspots
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Sunspot, initial time evolution
![Page 31: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/31.jpg)
Sunspot, time evolution (rep.)
![Page 32: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/32.jpg)
Temperature, hor. & vert. magn. field,hor. & vert. velocity, surface intensity
![Page 33: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/33.jpg)
Velocity, as seen by VAPOR(top perspective)
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Sunspot,log magnetic pressure
![Page 35: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/35.jpg)
Sunspot, field lines with density iso-surface (~solar surface)
![Page 36: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/36.jpg)
Field line detail
![Page 37: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/37.jpg)
Key result: A continuous solar velocity spectrum
Supergranulation may stand out a little
But the flow is nearly scale-invariant amplitudes scale inversely with size lifetimes scale with the square of the size
![Page 38: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/38.jpg)
Data sets available onStanford Helioseismology Archive
![Page 39: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/39.jpg)
Experiments:Forthcoming
AR magnetic fields add B from MDI magnetogram (as in Gudiksen &
Nordlund)
Quiet Sun magnetic fields advect initially horizontal field from the bottom b.c.
Rise of magnetic flux tube Insert flux tube near bottom, study emergence through
surface
Coronal & chromospheric heating similar to Gudiksen & Nordlund, but “real driving”
![Page 40: Numerical Simulations of Supergranulation and Solar Oscillations Åke Nordlund Niels Bohr Institute, Univ. of Copenhagen with Bob Stein (MSU) David Benson,](https://reader035.fdocuments.in/reader035/viewer/2022062519/56649cab5503460f9496c468/html5/thumbnails/40.jpg)
The End The End