SST Rank histogram at global, NAtl(20-70N, 110W-40E) and WNPac(20-70N, 110E-180) HadISST as observation data. Rank histogram is ranking frequency of observation data with ensemble members. ie. Histogram all flat -> good ensemble Large at most right bin -> model members are overestimate. Large at most left bin -> model members are underestimate. Bell shape -> model simulation is too diverse. Inverted bell shape -> model simulation is too concentrated.