资源环境科技发展态势分析平台

The 2018 central Pacific (CP) El Niño preceded the 2019 strong positive Indian Ocean Dipole (pIOD). The robustness of a CP El Niño preconditioning a strong pIOD has not been investigated. Here we show that March‐April‐May (MAM) easterly anomalies over the equatorial eastern Indian Ocean (EIO) induced by a preceding CP El Niño drive a thermocline shallowing conducive to an early equatorial EIO cooling. However, the same winds also generate off‐equatorial downwelling Rossby waves in the southern EIO, which reflect as downwelling Kelvin waves, able to weaken the initial anomalies. Further, zonal winds in June‐July‐August (JJA) can either be beneficial or unfavourable for the developing pIOD. Only when the equatorial easterlies, EIO cooling, and thermocline shallowing are sufficiently amplified by JJA does a strong pIOD occur. Despite this, a multi‐century model simulation suggests that development of majority of strong pIOD events is facilitated by a preceding CP El Niño.