indeed, we should not forget that the observed sea surface height is negative for this case. Additionally, in this model, the SLP anomaly between the SST and the wind is omitted. Yet, in a common sense consideration, the response of the SLP to the SST and its effect on the wind depend on their distributions in space (maybe in the whole tropical Pacific, even in the extra-tropical Pacific), and it is unconvincing to confine them to the equator with a trivial hypothesis, as is made for the Bjerknes feedback. Details of their precise relationships are still awaiting further investigation.

\(3) The recharge oscillator model can be seen as a developed version of the previous two, where emphasis is placed on thermocline feedback. The affecting sequence of this models is: an SST anomaly in the CP and EP (with a thermoclinic anomaly in the west), a wind anomaly (accompanied by an abrupt adjustment of the thermocline), a current anomaly (including zonal and meridional flows), and then an SST anomaly in the CP and EP (caused by an adjustment of the thermocline). From the viewpoint of the fundamental dynamic ring, its progress lies in stressing the effects of zonal and meridional currents. 