Study Of The Teleconnection Of The Traditional Ni(?)o Indices To The Global Ocean And The Feasibility Of A Unified Ni(?)o Region

The ENSO (El Ni(?)o/Southern Oscillation) phenomenon is one of consequencesafter strong ocean-atmosphere interactions mainly in the equatorial Pacific Ocean,usually including two important episodes: the El Ni(?)o event and the La Ni a event.By using both the satellite and the field measurement reanalysis data, we carry outsome studies of the ENSO teleconnections in the global oceans by analyzing thecorrelation between the various currently existing Ni(?)o region indices andtemperature anomalies of the ocean waters. Because there are several Ni(?)o indicesdepicting ENSO events concurrently now, we also try to discuss the feasibilities of aunified Ni(?)o region and Ni(?)o indices.Firstly, this study carries out some analysis of the lead-lag correlation between thetraditional Ni(?)o3.4indices and the three-dimensional global oceanic temperatureanomalies. The lead-lag correlation maps for different depths of the upper oceansshow fairly complicated information, indicating that ENSO event is far from beingonly a surface air-sea interaction event along the equatorial Pacific Ocean. Animportant finding is that the water mass near the depth of160m around200°E,2°Smight be a very good precursor of the ENSO event leading ahead by around11-month with a significant correlation high than0.8. This study might be one of thefirst to precisely locate the potential ENSO predictor, which is believed to benefit thefuture ENSO forecast.Secondly, the teleconnections of the newly proposed EP (Eastern Pacific) and CP(Central Pacific) ENSO signals to the global ocean are compared. EP ENSO signalhas stronger and wider global teleconnection. During EP ENSO event development,the eastern equatorial Pacific Ocean shows stronger and wider positive SSTanomalies, and so does the Indian Ocean. The northern Pacific Ocean showsnegative SST anomalies.The heat content anomalies show opposite phasedistribution between the eastern and the western equatorial Pacific Ocean, the heat content anomalies in the eastern equatorial Pacific Ocean are positive while those inthe western equatorial Pacific Ocean are negative. And when EP El Ni(?)o happens,western wind stress anomalies are obvious in the whole equatorial Pacific Ocean.The CP ENSO signal, however, has weaker global teleconnection. During itsdevelopment, the central equatorial Pacific Ocean shows much weaker positive SSTanomalies. Part of the northern Pacific ocean has similar SST anomaly phase withthe central equatorial Pacific ocean while the Indian Ocean has little teleconnectionto the CP ENSO signals. And the heat content only shows positive anomalies in thecentral equatorial Pacific Ocean. At the same time, when CP El Ni(?)o happens,westerly wind stress anomalies appear in the western equatorial Pacific Ocean andeasterly wind stress anomalies appear in the eastern equatorial Pacific Ocean, both ofwhich are weak. This study shows that the EP and CP ENSO events show significantdifferences not only along the equatorial Pacific Ocean but also in other oceanregions, which hints that they may be subject to two different dynamic mechanismsand needs further studies.Finally, based on analyzing variabilities of global SST (Sea Surface Temperature)anomalies, this study suggests a unified Ni(?)o index using the surface thermalcentroid anomaly of the region along the Pacific equator embraced with the0.7°Ccontour line of the standard deviation of the SST anomalies and tries to unify thetraditional Ni(?)o regions into a single one. The unified Ni(?)o region covers almost allthe traditional Ni(?)o regions. The zonal centroid anomalies of unified Ni(?)o region arefound helpful in the classification of the EP (Eastern Pacific)/CP (Central Pacific)types of El Ni(?)o events. All the current Ni(?)o indices can be well-given by simplelinear combination of unified Ni(?)o indices, which hints that the SST anomaly andthermal centroid location anomaly of the unified Ni(?)o region would yield a morecomplete image of each El Ni(?)o/La Ni a event.