In the boreal spring of 2023, an extreme coastal El Niño struck the coastal regions of Peru and Ecuador, causing devastating rainfalls, flooding, and record dengue outbreaks. Observations and ocean model experiments reveal that northerly alongshore winds and westerly wind anomalies in the eastern equatorial Pacific, initially associated with a record-strong Madden-Julian Oscillation and cyclonic disturbance off Peru in March, drove the coastal warming through suppressed coastal upwelling and downwelling Kelvin waves. Atmospheric model simulations indicate that the coastal warming in turn favors the observed wind anomalies over the far eastern tropical Pacific by triggering atmospheric deep convection. This implies a positive feedback between the coastal warming and the winds, which further amplifies the coastal warming. In May, the seasonal background cooling precludes deep convection and the coastal Bjerknes feedback, leading to the weakening of the coastal El Niño. This coastal El Niño is rare but predictable at 1 month lead, which is useful to protect lives and properties.

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2023年极端沿海厄尔尼诺现象：大气和海气耦合机制

2023 年的北方春季，极端沿海厄尔尼诺现象袭击了秘鲁和厄瓜多尔沿海地区，造成毁灭性降雨、洪水和创纪录的登革热疫情。观测和海洋模型实验表明，赤道东部太平洋的偏北沿岸风和西风异常最初与三月份秘鲁海域创纪录的强烈马登-朱利安振荡和气旋扰动有关，通过抑制沿海上升流和下降流开尔文推动了沿海变暖。波浪。大气模型模拟表明，沿海变暖反过来通过引发大气深层对流而有利于远东热带太平洋上空观测到的风异常。这意味着沿海变暖与风之间存在正反馈，从而进一步放大了沿海变暖。 5月，季节性背景变冷阻碍了深层对流和沿海比耶克内斯反馈，导致沿海厄尔尼诺现象减弱。这次沿海厄尔尼诺现象很少见，但提前 1 个月可预测，这对于保护生命和财产很有用。