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تسجيل مستخدم جديدDispersion of the solar magnetic flux in undisturbed photosphere as derived from SDO/HMI data
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Valentina Abramenko
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To explore the magnetic flux dispersion in the undisturbed solar photosphere, magnetograms acquired by Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamic Observatory (SDO) were utilized. Two areas, a coronal hole area (CH) and an area of super-granulation pattern, SG, were analyzed. We explored the displacement and separation spectra and the behavior of the turbulent diffusion coefficient, $K$. The displacement and separation spectra are very similar to each other. Small magnetic elements (of size 3-100 squared pixels and the detection threshold of 20 Mx sm$^{-2}$) in both CH and SG areas disperse in the same way and they are more mobile than the large elements (of size 20-400 squared pixels and the detection threshold of 130 Mx sm$^{-2}$). The regime of super-diffusivity is found for small elements ($gamma approx 1.3 $ and $K$ growing from $sim$100 to $sim$ 300 km$^2$ s$^{-1}$). Large elements in the CH area are scanty and show super-diffusion with $gamma approx 1.2$ and $K$ = (62-96) km$^2$ s$^{-1}$ on rather narrow range of 500-2200 km. Large elements in the SG area demonstrate two ranges of linearity and two diffusivity regimes: sub-diffusivity on scales (900-2500) km with $gamma=0.88$ and $K$ decreasing from $sim$130 to $sim$100 km$^2$ s$^{-1}$, and super-diffusivity on scales (2500-4800) km with $gamma approx 1.3$ and $K$ growing from $sim$140 to $sim$200 km$^2$ s$^{-1}$. Comparison of our results with the previously published shows that there is a tendency of saturation of the diffusion coefficient on large scales, i.e., the turbulent regime of super-diffusivity is gradually replaced by normal diffusion.
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