Subsurface ocean temperature indices for Central-Pacific and Eastern-Pacific types of El Niño and La Niña events
Subsurface ocean temperature indices for Central-Pacific and Eastern-Pacific types of El Niño and La Niña events
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DOI：
10.1007/s00704-010-0307-6
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发表时间：
2011-03
影响因子：
3.4
通讯作者：
Jin‐Yi Yu;H. Kao;Tong Lee;Seon Tae Kim
中科院分区：
文献类型：
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作者：
Jin‐Yi Yu;H. Kao;Tong Lee;Seon Tae Kim
制定次表层海洋温度指数是为了识别两种不同类型的热带太平洋变暖（厄尔尼诺）和冷却（拉尼娜）事件：东太平洋（EP）类型和中太平洋（CP）类型。赤道东太平洋（80°W-90°W，5°S-5°N）和赤道中太平洋（160°E-150°W，5°S-5°N）上层100 m的海温距平分别构成EP和CP次表层指数。使用海洋数据同化产品的1958-2001年期间进行的分析。结果发现，EP/CP次表层指数的相关性较低，表现出更强的偏态比海表温度（SST）为基础的指数。此外，虽然准两年（102年）和准四年（104年）的周期性出现在这两种类型的SST为基础的指数，地下指数仅占主导地位的准两年周期的CP型和准四年（104年）的EP型周期。低相关性、高偏度和单前导周期性是定义区分EP和CP类型的指数的理想属性。使用次表层指数，由Niño-3.4 SST指数识别的主要厄尔尼诺和拉尼娜事件被分类为分析期间的EP或CP类型。结果表明，强厄尔尼诺事件多为EP型，强拉尼娜事件多为CP型。研究还发现，强CP型拉尼娜事件往往发生在强EP型厄尔尼诺事件之后。相反的子序列（即，强EP厄尔尼诺事件发生在强CP拉尼娜事件之后）似乎并不典型。研究表明，次表层海洋指数是识别太平洋厄尔尼诺和拉尼娜事件EP和CP类型的有效方法。
Subsurface ocean temperature indices are developed to identify two distinct types of tropical Pacific warming (El Niño) and cooling (La Niña) events: the Eastern-Pacific (EP) type and the Central-Pacific (CP) type. Ocean temperature anomalies in the upper 100 m are averaged over the eastern (80°W–90°W, 5°S–5°N) and central (160°E–150°W, 5°S–5°N) equatorial Pacific to construct the EP and CP subsurface indices, respectively. The analysis is performed for the period of 1958–2001 using an ocean data assimilation product. It is found that the EP/CP subsurface indices are less correlated and show stronger skewness than the sea surface temperature (SST)-based indices. In addition, while both quasi-biennial (∼2 years) and quasi-quadrennial (∼4 years) periodicities appear in the SST-based indices for these two types, the subsurface indices are dominated only by the quasi-biennial periodicity for the CP type and by the quasi-quadrennial (∼4 years) periodicity for the EP type. Low correlation, high skewness, and single leading periodicity are desirable properties for defining indices to separate the EP and CP types. Using the subsurface indices, major El Niño and La Niña events identified by the Niño-3.4 SST index are classified as the EP or CP types for the analysis period. It is found that most strong El Niño events are of the EP type while most strong La Niña events are of the CP type. It is also found that strong CP-type La Niña events tend to occur after strong EP-type El Niño events. The reversed subsequence (i.e., strong EP El Niño events follow strong CP La Niña events) does not appear to be typical. This study shows that subsurface ocean indices are an effective way to identify the EP and CP types of Pacific El Niño and La Niña events.