Predictability of the Chile Niño/Niña.

The recently discovered Chile Niño/Niña is an intrinsic coupled climate mode in the southeast Pacific, which influences both regional climate and marine ecosystem. Using Scale Interaction Experiment‐Frontier version 2 seasonal prediction system, it is shown that the Chile Niño/Niña can be skillfully predicted up to 3‐month lead. Although the occurrences and related climate impacts of the Chile Niño/Niña are captured by the prediction system, the predicted magnitudes are weaker than observations in the ensemble mean. Further analyses of the inter‐member relationships indicate that the Chile Niño/Niña predictability depends on how well the coastal ocean‐atmosphere‐land positive feedback among alongshore surface winds, coastal upwelling and the sea surface temperature anomalies is captured. The insufficient reproduction of this essential feedback is responsible for the underestimated magnitude. Therefore, accurately predicting the Chile Niño/Niña remains a challenge. Improving model resolution and ensemble size may be a key to enhancing prediction skills of the coastal climate modes along the eastern boundary upwelling systems. Plain Language Summary: The Chile Niño/Niña is an El Niño–Southern Oscillation‐like phenomenon off northern Chile, which is generated by intrinsic coastal air‐sea‐land interaction. The occurrences of Chile Niño/Niña not only influence the production of marine ecosystem, but also exert impacts on terrestrial climate over the South America. For example, an off‐Chile sea surface temperature warm event induced catastrophic floods over Chile's Atacama Desert in March 2015, causing huge casualties and economic losses. Therefore, skillfully predicting the Chile Niño/Niña is crucial for mitigating climate disasters to benefit the livelihood of people. Based on a state‐of‐the‐art seasonal prediction system, the Chile Niño/Niña and associated climate impacts are found to be predictable one season ahead. We also found that the key to predict the Chile Niño/Niña lies in the realistic simulation of coastal ocean‐atmosphere‐land positive feedback in the southeast Pacific. Our study discusses the predictability of the Chile Niño/Niña for the first time, which may contribute to improving the seasonal prediction of coastal climate modes discovered in the eastern boundary upwelling regions of the major oceans. Establishing an early warning system for such a climate mode may contribute to reducing the socioeconomic losses. Key Points: As an intrinsic coastal climate mode, the Chile Niño/Niña has noticeable impacts on regional climate and marine ecosystemThe occurrences of Chile Niño/Niña events are found to be predictable up to 3 months ahead for the first timeThe Chile Niño/Niña predictability is underpinned by the coastal ocean‐atmosphere‐land positive feedback [ABSTRACT FROM AUTHOR]