Turbulence in the solar photosphere as derived from NST observations of the granulation
Abstract
We present results of analysis of images of solar granulation obtained with BBSO’s 1.6 m clear aperture New Solar Telescope (NST) at BBSO. Observations were carried out on 2009 July 21 near the central meridian of the solar disk in the TiO (705 nm) spectral line. Eleven consecutive 30s bursts were speckle reconstructed to derive the transverse velocity map, as well as the power spectra of the velocity and temperature fluctuations. The FOV was about 60x60 arcsec. We found that the transverse velocity spectrum displays the classical Kolmogorov-type turbulent exponent, -5/3 over spatial scales of 1-8 Mm, while below 1 Mm we observe a dissipative spectrum characterized by an exponent of -7/2. The observed dissipation regime is much more moderate than the -17/3 regime, which is typical for the classical turbulence and was reported earlier for the Doppler velocities in the photosphere of the quiet sun. One might conclude that on scales below 1 Mm the turbulence is being suppressed by the presence of the magnetic field. The temperature spectrum displays a very narrow Kolmogorov-type spatial range of 0.9 - 0.5 Mm, which is followed at smaller scales by the -3.5 range. Again, the dissipation of the temperature fluctuations does not follow the classical dissipation regime. Joint consideration of the velocity and temperature spectra shows that there seems to be no reasonable possibility to interpret them in framework of the highly developed isotropic turbulence of a fluid flow. We shall discuss the implications of these results, as well as more recent results.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMSH51A1256A
- Keywords:
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- 7529 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY / Photosphere;
- 7863 SPACE PLASMA PHYSICS / Turbulence