Fig. 2

Zonal mass stream function regressed onto the Niño3.4 SST index during boreal winter (10⁹ kgs⁻¹ °C⁻¹). Color-mapping shows the regression coefficients of the zonal mass stream function in a reanalysis datasets, b AMIP5 models, c AMIP6 models, d CMIP5 models and e CMIP6 models. Gray dotted areas in a–e indicate that regression coefficients are significant at the 95% confidence level. f The quantification of the mass stream function responses to the ENSO-related SST forcing in different datasets. The white lines show the regression coefficients, and the ranges of the bars indicate the 95% confidence interval of these regression results with Student’s t test. g Is the box–whisker plots to indicate the spread of the reanalysis and model representation. On each box, the central line is the median, and the bottom and top edges of the box is the 25th and 75th percentiles, respectively. The whiskers extend to the most extreme data points not considered outliers. The ‘+’ symbol is the outliers in reanalyses or models