Spatial variations in the velocity field and real solar granulation

Abstract

In this paper, the physical conditions within the inhomogeneous solar atmosphere have been reconstructed by means of solving the inverse problem of non-local thermodynamic equilibrium (NLTE) radiative transfer. The profiles of the λ= 523.42 nm Fe i spectral line of high spatial and time resolution were used as observational data. The velocity field has been studied for the real solar granulation in the superadiabatic layer and overshooting convection region. Also, we investigate the vertical structure of the inhomogeneous solar photosphere and consider the penetration of granules from the convective region into the upper layers of the stable atmosphere. The microturbulent velocity appears to be minimal at the bottom of the overshooting convection region and increases sharply through the superadiabatic layer and upper photosphere. High-turbulence layers emerge either in the central part of a flow or at the boundary of an incipient flow with subsequent drift towards the centre of the flow. Wide descending flows tend to disintegrate into structures having turbulence augmented and these structures correspond to the flows of matter. High microturbulence of the intensive flows provokes steep temperature depression in the upper photosphere leading to the second inversion of temperature for the intergranules. The inversion of vertical velocities is observed to be frequent in the solar granulation. Some of the convective flows reach the minimum temperature region. Vertical convective velocities of the matter flows are found to be smaller in the middle and upper photosphere. Also, the effect of finite resolution on spatial variations of the velocities in the solar photosphere has been estimated.