Extended Data Fig. 7: Principal components reconstruction.
From: ENSO complexity controlled by zonal shifts in the Walker circulation
a-e, Scatter plots between sea surface temperatures (SST) at different longitudes of the equatorial Pacific and first principal component timeseries of SST (PC1), as computed from observations. f-j, Analysis repeated for SSTs generated by the model. The present representation helps determine how well data is aligned with (and thus captured by) the SST reconstruction R1 from the first PC (black lines, see methods). Individual SST realizations are discriminated in terms of their belonging to the warm pool region where they saturate around 29∘C (WP, red) or cold tongue region where they slope (CT, blue), with total occurrences indicated in %. Where WP and CT occurrences are more alike (that is mixed), the SST variability is no longer captured by R1 but by R1 + R2* (green lines) where R2* is a nonlinear imprint of the first PC on the second PC (see methods).
