Extended Data Fig. 3: Phase space evolution.
From: ENSO complexity controlled by zonal shifts in the Walker circulation
a,b, Timeseries of warm pool extent χ and basin-wide heat content hM obtained from a numerical integration of the oscillator model (Eq. (1)), and which represents ENSO variability. Warm pool extent χ within 0-1 corresponds to a warm pool edge position within 120∘E-80∘W. Shading indicates the hand-picked period used in other figures. c,d, Kernel density estimates (filled contours) and individual realizations (black lines) in phase space of warm pool extent χ and basin-wide heat content hM, compared between observations and model solutions. For clarity, density estimates are shown only above 0.04% where they hide individual realizations that are too dense to visualize. Phase space is divided into El Niño or La Niña states as well as recharged or discharged states as defined here with respect to average conditions (white dashed lines). El Niño events may reach larger amplitudes than La Niña events but are more short-lived.
