indices separately. As for that of Niña-A, it has a different definition. Since it is used to detect the inclined streams from the southeast to the central equatorial Pacific, the dominating zonal component of the velocity is mainly concerned (see ). As for the equatorward component (see ), it can be borrowed to estimate the slant angle of the mean stream, which in turn determines the anticipated scope of the negative anomaly on the equator.

In addition to the contribution of the CECC, the occurrence of positive SST anomalies should be related to the four indices in the EP. A comparison of and together with shows good consistency between these indices and the anomalies: (1) The prominent maximum value of Niño-B index in 1997 agrees well with the positive SST anomaly in the EP (the leading time was not obvious). For this case, Niño-A index just decreased to zero, so the anomaly in the EP was fully dominated by Niño-B index. (2) The prominent maximum values of Niño-A index in 1994, 2002, 2004 and 2006 agree well with the positive SST anomalies in the CP (the leading times were 0–3 months). (3) Both Niño-A and Niño-B indices were high during 