Mass flux in the magnetically open regions. The black curve represents the mass flux as a function of height averaged over an ∼8-hour period and across the horizontal directions. The yellow region indicates the temporal variability of the mass flux, estimated as the standard deviations of different snapshots divided by the square root of the number of snapshots. The blue dashed line shows the zero flux. On average, above ∼7 Mm the mass flows upwards, below it flows downwards.