Relationship between active region lifetime and total magnetic flux. Middle panel: simulated and observed lifetimes of active regions as functions of their total unsigned flux. Blue markers are simulated lifetimes obtained from SFT simulations using NSO/SOLIS and HMI synoptic maps. Red markers are observed lifetimes obtained from SOLIS full-disk magnetograms. The solid blue and red curves show the median flux in lifetime bins with a width of one day for simulated and observed lifetimes, respectively. The blue and red bars on the left and right show the number of active regions in each bin.