Fig. 6: A case study for the 2015/16 super El Niño.

a Niño3.4 SST anomaly evolution: observations (black), March-initialized ECTL prediction (thick blue lines), O-CNOP-based ensemble mean (ECNOP; thick red lines), and individual ensemble members (colored thin lines). b Niño3.4 SST prediction errors: ECTL (black), ECNOP (green), and O-CNOP optimization rate (purple).