SIC in March averaged over the year 2007-2016 in INTAROS-opt (a), the TOPAZ4 reanalysis (b), and the PIOMAS reanalysis (c). Panels (d)-(f) are the corresponding SIC in September. The red dotted lines are the satellite-observed sea ice edge (15%) , and the black dashed lines in panels (a) and (d) are the sea ice edge in INTAROS-ctrl.