ENSO.Another signature of the ENSO regime change is manifested by the frequentoccurrence of Warm-Pool (WP) type ENSO that accompanies SSTAs centered over thecentral Pacific near the WP edge and exhibits characteristics differing from those of CTENSO.The distinct manifestations of the two types of ENSO in this ENSO regimechange are identified clearly by removing the strong background decadal signal.Sincethe late 1970s,the WP ENSO features a weak eastward (westward) propagation of SSTAcenter in developing (decaying) phase,which makes no net contribution to the observedeastward propagation,and features a 2-3-yr period compared to the 4-5-yr period of theCT ENSO.Observations strongly suggest that WP and CT ENSO are independent quasi-biennial and quasi-quadrennial modes of the tropical Pacific climate variability,respectively,and that these two ENSO modes have coexisted actively since the late 1970swhen either El Nino or La Nina can be separated into the two types.