• Limited impacts of March MJO on El Niño evolution: extra atmospheric experiments

In the paper entitled "North Pacific meridional mode has larger impacts on El Niño evolution than the March Madden-Julian Oscillation" by Yu Liang1*, Shang-Ping Xie1, Alexey Fedorov2,3, Stephen G. Yeager4 To validate that the atmospheric ensemble spread in March primarily reflects internal atmospheric variability with minimal influence from the SST spread (cf. Figs. 5F and 6F), we perform additional atmospheric model experiments using CAM6. In the Control experiment, CAM6 is forced with perpetual climatological March conditions (i.e., SST and insolation) and integrated for five years following a two-year spin-up. In the first perturbation experiment, the SST anomalies shown in Fig. 5F are added to the SST forcing field, and the model is integrated for five years. In the second perturbation experiment, the SST anomalies shown in Fig. 6F are similarly added. The atmospheric responses to the imposed SST anomalies are presented in Fig. S7.