Observed ENSO and SAM relationship in 1979–2016. Scatter diagrams of Niño3.4 SST anomalies versus (a) SAM, (b) de-trended SAM, and (c) de-trended residual SAM after removing the influence of the Antarctic stratospheric vortex on SAM by using a linear regression. 1979–2016 October-November-December (OND) data are displayed in each diagram. The standardized Niño3.4 SST and SAM values are shown. The correlation of the SAM indices with Niño34 is displayed in the upper right of each panel. Correlation greater than |0.33| is statistically significant correlation at the 5% level (assuming 38 samples). The impact of de-trending the SAM index on the strength of the correlation with Niño3.4 SST is negligible as shown in (b).