Three evolution patterns of Central-Pacific El Nino

Three evolution patterns are identified for the Central Pacific (CP) type of El Nino based on events that occurred during 1958-2007: (1) a symmetric-decaying pattern whose sea surface temperature anomalies grow and decay symmetrically with respect to a peak phase; (2) a prolonged-decaying pattern that decays slowly and is followed by a warm event in the eastern Pacific (EP); and (3) an abrupt-decaying pattern that terminates rapidly after the peak and is followed by a cold event in the EP. The depth of the equatorial thermocline is found to determine which evolution pattern occurs. If the CP El Nino occurs in a recharged thermocline state (i.e., deeper-than-normal depth), an EP warming may appear in the decaying phase of the CP event to slow down the decay, giving rise to the prolonged-decaying pattern. If the thermocline is in a discharged state (i.e., shallower than-normal depth), an EP cooling may occur to abruptly terminate the CP El Nino. If the thermocline is in a neutral state (i.e., normal depth), the CP event may have a symmetric pattern of growth and decay. Although a few exceptions exist, these results indicate that the equatorial thermocline state at the peak phase of a CP El Nino event can be a potential predictor of the way the event may decay. Citation: Yu, J.-Y., and S. Tae Kim (2010), Three evolution patterns of Central-Pacific El Nino, Geophys. Res. Lett., 37, L08706, doi:10.1029/2010GL042810.