两种类型厄尔尼诺事件发生前大气和海洋状况的对比分析

        The atmospheric and oceanic conditions before the onset of EP El Niño and CP El Niño in nearly 30 years are compared and analyzed by using 850 hPa wind, 20°C isotherm depth, sea surface temperature and the Wheeler and Hendon index. The results are as follows: In the western equatorial Pacific, the occurrence of the anomalously strong westerly winds of the EP El Niño is earlier than that of the CP El Niño. Its intensity is far stronger than that of the CP El Niño. Two months before the El Niño, the anomaly westerly winds of the EP El Niño have extended to the eastern Pacific region, while the westerly wind anomaly of the CP El Niño can only extend to the west of the dateline three months before the El Niño and later stay there. Unlike the EP El Niño, the CP El Niño is always associated with easterly wind anomaly in the eastern equatorial Pacific before its onset. The thermocline depth anomaly of the EP El Niño can significantly move eastward and deepen. In addition, we also find that the evolution of thermocline is ahead of the development of the sea surface temperature for the EP El Niño. The strong MJO activity of the EP El Niño in the western and central Pacific is earlier than that of the CP El Niño. Measured by the standard deviation of the zonal wind square, the intensity of MJO activity of the EP El Niño is significantly greater than that of the CP El Niño before the onset of El Niño.

        本文利用850hPa风、20°C等温线深度、海面温度、Wheeler和Hendon指数对近30年来厄尔尼诺和厄尔尼诺爆发前的大气和海洋条件进行了对比分析。结果表明：在赤道西太平洋，极压厄尔尼诺异常强西风的出现早于极压厄尔尼诺，其强度远强于极压厄尔尼诺，厄尔尼诺的异常西风已经扩展到东太平洋地区，而CP厄尔尼诺的异常西风只能在厄尔尼诺发生前3个月扩展到日界线的西面，以后还停留在那里。与极压厄尔尼诺现象不同，极压厄尔尼诺现象在发生前总是与赤道太平洋东部的东风异常有关。厄尔尼诺现象的温跃层深度异常可以明显向东移动并加深。此外，我们还发现温跃层的演化超前于厄尔尼诺的海表温度的发展，西太平洋和中太平洋厄尔尼诺的强MJO活动早于厄尔尼诺的强MJO活动厄尔尼诺现象明显大于厄尔尼诺爆发前的厄尔尼诺现象。

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Citation (引用): ZHI Xie-fei, YANG Hua, XU Shu-wen, et al. A comparative analysis of atmospheric and oceanic conditions before the occurrence of two types of El Niño events [J]. J Trop Meteor, 2019, 25(1): 34-44, https://doi.org/10.16555/j.1006-8775.2019.01.004.