Fig. 1: Observed La Niña onset diversity.
a Time evolution of detrended ONI from 1910 to 2020 (units: °C). Red, blue, green and white bars denote El Niño, single-year and the first year of multi-year La Niña, the second and third year of the multi-year La Niña, and neutral years, respectively. Dashed lines are ±0.5 °C. The “N”, “C”, and “S” in the bottom represent that the La Niña onset types are “neutral year to La Niña” (N2L), “central Pacific El Niño to La Niña” (CE2L) and “super El Niño to La Niña” (SE2L), respectively. Time-zonal sections of SSTA (shaded, units: °C) and SSTA tendency (contour, units: °C mon−1) along the equator (within 5°S–5°N) for b N2L, c CE2L and d SE2L. Solid (dashed) lines represent the positive (negative) SSTA tendencies. Purple dots are the maximum negative SSTA center where SSTA exceeds −0.45 °C. Black dots represent SSTA that exceeds the 95% confidence level. Purple boxes denote La Niña onset phases. “−1” and “0” represent the preceding and developing year of La Niña.
