不同强度El Nino的衰减过程.Ⅱ,中等和较弱El Nino的衰减过程

The decay of El Nino with different intensity. Part Ⅱ,The decay of the moderate and relatively-weak El Nino

在第二部分,我们研究了中等和较弱El Ni(?)o的衰减过程.结果表明,对中等El Ni(?)o而言,在其发展阶段和盛期,负异常信号在西太平洋产生,但由于强度不足,在El Ni(?)o盛期之后迅速衰减,这是一种夭折的类西太平洋振子过程.因此,与强El Ni(?)o不同,中等El Ni(?)o衰减进入平常态.而较弱El Ni(?)o以截然不同的另一种方式进行位相转换,伴随东南太平洋副高的加强和西移,东风异常和海表温度负异常自赤道东太平洋向西扩展,这是一种平流模态过程,导致较弱El Ni(?)o衰减进入La Ni(?)a.

In Part II, we explored the decaying processes of moderate and relatively-weak E1 Nino. The results show that, for the moderate E1 Nino, the anomaly signals appear in the development and peak phase, then they decay quickly after the peak phase due to the insufficient intensity of the E1 Nino. This is similar to the abortion of the western-Pacific-oscillation process. For this reason, different from the strong E1 Nifm, the transition from the moderate E1 Nino turns into a normal state. For the relatively-weak E1 Nino, its phase transition is controlled by a different mechanism. With the enhancement and westward movement of the subtropical high over the southeastern Pacific, the easterly and sea surface temperature anomalies also extend westward from the tropical eastern Pacific. The above process is an advective mode that causes the relatively E1 Nino turning into La Nifia.