Properties of Granules in Upflows and Downflows

Normal-mode observations of seven quiet regions, obtained by the Hinode spacecraft, are used to analyze the physical properties of granules with mean upward and downward Doppler velocity. We identify 75 146 granules from the observations with a granule-detection method. Then the granules are divided into two subsets: one with negative mean Doppler velocity (granule-upflows), and the other with positive mean Doppler velocity (granule-downflows). Next, the statistical properties and distributions of these two subsets of granules are measured and discussed. We also study the relation between the Doppler velocity of granules and other properties.