Peculiarities of solar photospheric convection at granular, mesogranular and supergranular scales

1Baran, OA, 1Stodilka, MI
1Astronomical Observatory of Ivan Franko National University of Lviv, Lviv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2014, 30(4):23-37
Start Page: Solar Physics
Language: Ukrainian

Power spectra of temperature and vertical velocity variations in the solar photosphere were calculated by using observational data of neutral iron line λ ≈ 639.3 nm obtained with the 70-cm German Vacuum Tower Telescope (Canary Islands, Spain) around the centre of the solar disc in the non-pertubed region. We analyzed the power spectra change with height. In the lower photosphere the main power is localized in the range corresponding to granulation with a peak at scales of about 1.5...2.0 Mm and decreases with height. In the upper photosphere maximum of the power spectrum is shifted towards larger scales ( Δλ ≈≤ 1 Mm); the power of vertical velocity fluctuations of supergranulation (λ ≈ 20...30 Mm) practically does not change with height; a separate regime of mesogranulaton (λ ≈ 5...12 Mm) was not found at all altitudes under study. Аccording to our results, the convective structure of the solar photosphere on mesogranular scales behaves like the granulation, namely, me-sostructures appear as a part of a broad distribution of granular scales. It is shown that supergra-nular flows are stable along the whole photosphere and reach much higher layers than the granular ones.

Keywords: granulation, photosphere, Sun

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