Scaled magnetic flux densities at four altitudes from photosphere to the source surface(1R_S, 1.5R_S, 2.0R_S and 2.5R_S) for four data sets scaled to SOLIS (n_max = 90 for others, 9 for WSO). Upper panel: dark-green curve shows the observed (not PFSS modeled) unsigned magnetic flux density of SOLIS/VSM (360*180 resolution). Second and third panels: ⟨|B_r(r)|⟩ at r = 1.5R_s and r = 2.0R_s and fourth panel: at the source surface of r = 2.5R_s.