J/A+A/581/A67 Solar supergranular velocity profiles (Langfellner+, 2015)
Spatially resolved vertical vorticity in solar supergranulation using
helioseismology and local correlation tracking.
Langfellner J., Gizon L., Birch A.C.
<Astron. Astrophys. 581, A67 (2015)>
=2015A&A...581A..67L 2015A&A...581A..67L
ADC_Keywords: Sun
Keywords: convection - Sun: helioseismology - Sun: oscillations -
Sun: granulation
Abstract:
Flow vorticity is a fundamental property of turbulent convection in
rotating systems. Solar supergranules exhibit a preferred sense of
rotation, which depends on the hemisphere. This is due to the Coriolis
force acting on the diverging horizontal flows. We aim to spatially
resolve the vertical flow vorticity of the average supergranule at
different latitudes, both for outflow and inflow regions. To measure
the vertical vorticity, we use two independent techniques:
time-distance helioseismology (TD) and local correlation tracking of
granules in intensity images (LCT) using data from the Helioseismic
and Magnetic Imager (HMI) on board the Solar Dynamics Observatory
(SDO). Both maps are corrected for center-to-limb systematic errors.
We find that 8 h TD and LCT maps of vertical vorticity are highly
correlated at large spatial scales.
Description:
These tables give the azimuthally averaged horizontal velocity
components vr and vt for the average supergranular outflows and
inflows at various latitudes, as displayed for 40° latitude in
Fig. 13 in the paper. The velocities have been computed by the method
of local correlation tracking using intensity images from the
Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics
Observatory (SDO) spacecraft. The structures of all data files are
identical. The error estimates were computed by splitting the whole
observation period (112 days) in eight parts.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
p60_out.dat 49 136 +60° latitude, outflow
p60_in.dat 49 136 +60° latitude, inflow
p40_out.dat 49 136 +40° latitude, outflow
p40_in.dat 49 136 +40° latitude, inflow
p20_out.dat 49 136 +20° latitude, outflow
p20_in.dat 49 136 +20° latitude, inflow
0_out.dat 49 136 0° latitude, outflow
0_in.dat 49 136 0° latitude, inflow
m20_out.dat 49 136 -20° latitude, outflow
m20_in.dat 49 136 -20° latitude, inflow
m40_out.dat 49 136 -40° latitude, outflow
m40_in.dat 49 136 -40° latitude, inflow
m60_out.dat 49 136 -60° latitude, outflow
m60_in.dat 49 136 -60° latitude, inflow
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Byte-by-byte Description of file: *.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 Mm r [0.34/48] horizontal distance from outflow/inflow
center
11- 19 F9.4 m/s vr [-240/350] Radial velocity component
21- 29 F9.4 m/s e_vr [0.1/6.1] Error estimate of vr
31- 39 F9.4 m/s vt [-12/12] Tangential velocity component
41- 49 F9.4 m/s e_vt [0.04/0.8] Error estimate of vt
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Acknowledgements:
Jan Langfellner, jlangfe(at)astro.physik.uni-goettingen.de
(End) Jan Langfellner [Univ. Goettingen], Patricia Vannier [CDS] 15-Jul-2015