Box and whisker plot of the FWHM velocities at the locations that are indicated in Fig. 5 by colored plus signs (+) and crosses (×). The box extends over one standard deviation above and below the mean velocity of a 10 × 10 pixel region. The upper and lower whisker refer to the maximum and minimum velocity in that region, respectively. Blue and red refer to the location of persistent up- and downflows, respectively. The white horizontal line inside the boxes corresponds to the median velocity.