Fig. 6
Time series of parameter ensemble mean for all experiments: a–d experiments with an initial ensemble mean μinit of 0 (Exps. 1–4). The parameter ensemble spread (σ) for each experiment was: a 0.05; b 0.1; c 0.2; and d 0.4. Black lines represent the time series for a total of 50 trials for each setting. Red lines represent averaged time series of all trials. The origin of the time axis corresponds to T = 4 h for the nature run; e–h experiments where μinit = 0.55 (Exps. 5–8: red lines), and − 0.55 (Exps. 9–12: blue lines); e experiments where σ = 0.05 (Exps. 5 and 9); f σ = 0.1 (Exps. 6 and 10); g σ = 0.2 (Exps. 7 and 11); and h σ = 0.4 (Exps. 8 and 12). Initial times of the experiments were every 1 h from 3 h following the commencement of Exps.1–4. The estimation duration was 6 h for each experiment. The beginning and end points of estimation are denoted by circles and squares, respectively. Black lines represent the averaged time series of Exps.1–4, which are the same as the red lines in (a–d)