Fig. 1: Derivation of the SST pattern continuum.

a Hovmoller of SST in the Tropical Pacific (average 5° N–5° S), with seasonal variations removed and as a function of time (in years) and longitude. The black line indicates WPEP, roughly estimated from the 29 °C isotherm (see “Methods” section). b Same as a, but for SST anomalies (SSTA). c SST from (a) ordered by quantiles of WPEP (in %), thus with monotonous increase of WPEP (black line). d SSTA from (b) ordered by quantiles of WPEP (in %). Circles indicate individual ENSO events at their peak (Dec-Jan-Feb averages) in terms of longitude of max warming/cooling (circle position), overall intensity (circle size proportional to Niño 3.4 SSTA), and type (circle color: blue for La Niña, green for CP El Niño, and black for EP El Niño). e, f Same as (c, d), but quantile smoothed (i.e., smoothed horizontally) with a running-mean of 25 samples (circles from d are repeated). The quantile ordering and smoothing reveals spatial shifting on SST that approximately conserves structures, and gradual transitions between ENSO patterns on SSTA.