According to the review given by Jin and An (1999), thermocline feedback is known to play two roles in the ENSO: (i) a positive reinforcement for an SST anomaly to grow, and (ii) a turn-around mechanism for its phase transition. Though this viewpoint is overwhelming, to verify or deny it is not an easy matter. What we can say is that, this knowledge origins from the hypotheses that the ENSO cycle is a self-sustaining ocean–atmosphere system confined to the equator, and the SST in the CP and EP should be adjusted by an east–west seesaw oscillation. With the same understanding as for the previous models, not to say the SLP and wind anomalies are spatially dependent, a change of current may directly lead to a SST anomaly. So, the growth of a positive SST anomaly may be sustained with a supply of warm water, and a phase transition may occur naturally in case the warm water is replaced by a cold water, and vice versa. If these are verified, there will be no need to consider the underlying thermocline. To trace back for the term “El Niño", it was originally used to refer to the warm current that sets southward 