Changes in rainfall and surface zonal winds associated with extreme El Niño due to the ocean mean state difference. Estimates of air-sea coupling during present climate El Niño (pElNiño’; panels) and warmer climate El Niño (wElNiño’; middle panels). (a,b) Regression of rainfall anomalies onto the Niño3.4 SST anomalies (red box) of OND forecasts, using the 99 member ensemble. (c) Difference of regression coefficients between (a,b). The colour shading interval is 0.6 mm/day per 1 °C Niño3.4 SST anomaly beginning at +/−0.3 mm/day/°C. (d–f) Same as (a–c) except regression of the 10-m zonal wind anomalies onto the Niño3.4 SST anomalies (black box). The colour shading interval is 0.4 m/s per 1 °C Niño3.4 SST anomaly. Stippling indicates that regression coefficients in (a,b,d,e) and the differences of regression coefficients between pElNiño’ and wElNiño’ in (c) and (f) are statistically significant at the 5% level.