Fig. 1: Characteristics of simulated multi-year La Niña events.
From: Increased occurrences of consecutive La Niña events under global warming
a, Skewness of historical (1900–1999) Niño3.4 SST anomaly in observation (black bar) and CMIP6 models (coloured bars). The vertical line separates selected models with positive skewness (orange bars) from non-selected models with negative skewness (blue bars). The error bar denotes 1.0 s.d. of the inter-model spread in the selected (non-selected) MME. b, Temporal evolution of Niño3.4 SST anomaly composited for multi-year (red) and single-year (blue) La Niña events in the selected models over 1900–1999. Solid lines and shading indicate multi-model mean and 1.0 s.d. of a total of 10,000 inter-realizations based on a bootstrap method, respectively. Dashed lines indicate observations. The time series are smoothed with a three-month running-mean filter before analysis. The vertical grey shading denotes the time (October to February) when ENSO typically matures. c,d, Multi-model mean composite map of anomalous SST (°C; colouring) and surface wind stress (N m−2; vectors) for single-year (c) and multi-year (d) La Niña events during D(1)JF(2) in 1900–1999. Shown are values at which the ensemble mean exceeds 1.0 s.d. of the inter-model spread using a bootstrap method. Selected models simulate reasonably the observed evolution and pattern of multi-year La Niña.
