Dependence of the photospheric vertical flow characteristics on the granule dimension

The first high spectral resolution and white–light images obtained at the THEMIS telescope with the Italian Panoramic Monochromator (IPM), are analyzed to study in- tensity and velocity fluctuations in the photosphere of the sun. Monochromatic images, in two spectral ranges around 538.03 nm (C I line) and 557.61 nm (Fe I line), are used to char- acterize the vertical structure of the photosphere. Granulation cells and granules are obtained by segmentation of white-light images using suitable finding algorithms. We observe the height dependence of velocity vs. inten- sity fluctuations, and we found a dependence of velocity and intensity on granule dimension. Our results show that granules increase their intensity with dimension in the lower solar photo- sphere. In the higher photosphere, on the contrary, the intensity decreases with the dimension.